diff --git a/common/models/subscription.js b/common/models/subscription.js
index 84ec8c9..7594c23 100644
--- a/common/models/subscription.js
+++ b/common/models/subscription.js
@@ -537,7 +537,11 @@ module.exports = function(Subscription) {
     }
   }
 
-  Subscription.prototype.verify = async function(options, confirmationCode) {
+  Subscription.prototype.verify = async function(
+    options,
+    confirmationCode,
+    replace
+  ) {
     let mergedSubscriptionConfig = await Subscription.getMergedConfig(
       'subscription',
       this.serviceName
@@ -581,8 +585,31 @@ module.exports = function(Subscription) {
       error.status = 403
       return await handleConfirmationAcknowledgement(error)
     }
-    this.state = 'confirmed'
     try {
+      if (replace && this.userChannelId) {
+        let whereClause = {
+          serviceName: this.serviceName,
+          state: 'confirmed',
+          channel: this.channel
+        }
+        // email address check should be case insensitive
+        let escapedUserChannelId = this.userChannelId.replace(
+          /[-[\]{}()*+?.,\\^$|#\s]/g,
+          '\\$&'
+        )
+        let escapedUserChannelIdRegExp = new RegExp(escapedUserChannelId, 'i')
+        whereClause.userChannelId = {
+          regexp: escapedUserChannelIdRegExp
+        }
+        await Subscription.updateAll(
+          whereClause,
+          {
+            state: 'deleted'
+          },
+          options
+        )
+      }
+      this.state = 'confirmed'
       await Subscription.replaceById(this.id, this, options)
     } catch (err) {
       return await handleConfirmationAcknowledgement(err)
diff --git a/common/models/subscription.json b/common/models/subscription.json
index 1f21978..93e0c10 100644
--- a/common/models/subscription.json
+++ b/common/models/subscription.json
@@ -173,6 +173,15 @@
           "http": {
             "source": "query"
           }
+        },
+        {
+          "arg": "replace",
+          "type": "boolean",
+          "required": false,
+          "description": "whether or not replacing existing subscriptions",
+          "http": {
+            "source": "query"
+          }
         }
       ],
       "returns": [
@@ -202,9 +211,7 @@
       "returns": [
         {
           "arg": "result",
-          "type": [
-            "string"
-          ],
+          "type": ["string"],
           "root": true,
           "description": "operation outcome"
         }
@@ -218,4 +225,4 @@
       ]
     }
   }
-}
\ No newline at end of file
+}
diff --git a/docs/_docs/api-subscription.md b/docs/_docs/api-subscription.md
index 9076405..8b114c0 100644
--- a/docs/_docs/api-subscription.md
+++ b/docs/_docs/api-subscription.md
@@ -390,6 +390,11 @@ GET /subscriptions/{id}/verify
     * required: true
     * parameter type: query
     * data type: string
+  * whether or not replacing existing subscriptions
+    * parameter name: replace
+    * required: false
+    * parameter type: query
+    * data type: boolean
 * outcome
 
   *NotifyBC* performs following actions in sequence
@@ -397,9 +402,10 @@ GET /subscriptions/{id}/verify
   1. the subscription identified by *id* is retrieved
   2. for user request, the *userId* of the subscription is checked against current request user, if not match, error is returned; otherwise
   3. input parameter *confirmationCode* is checked against *confirmationRequest.confirmationCode*. If not match, error is returned; otherwise
-  4. *state* is set to *confirmed*
-  5. the subscription is saved back to database
-  6. displays acknowledgement message according to [configuration](../config-subscription#confirmation-verification-acknowledgement-messages)
+  4. if input parameter *replace* is supplied and set to *true*, then  existing confirmed subscriptions from the same *serviceName*, *channel* and *userChannelId* are deleted. No unsubscription acknowledgement notification is sent
+  5. *state* is set to *confirmed*
+  6. the subscription is saved back to database
+  7. displays acknowledgement message according to [configuration](../config-subscription#confirmation-verification-acknowledgement-messages)
       
 ## Update a Subscription
 ```
diff --git a/docs/_docs/config-subscription.md b/docs/_docs/config-subscription.md
index e5ebb8e..d8d708e 100644
--- a/docs/_docs/config-subscription.md
+++ b/docs/_docs/config-subscription.md
@@ -96,7 +96,7 @@ If error happened during subscription confirmation, query string *?err=\<error\>
 
 ## Duplicated Subscription
 *NotifyBC* by default allows a user subscribe to a service through same channel multiple times. If this is undesirable, you can set config *subscription.detectDuplicatedSubscription* to true. In such case instead of sending user a confirmation request, *NotifyBC* sends user a duplicated subscription notification message. Unlike a confirmation request, duplicated subscription 
-notification message doesn't and shouldn't contain any information to allow user confirm the subscription. You can customize duplicated subscription notification message by setting config *subscription.duplicatedSubscriptionNotification* in either *config.local.js* or using configuration api for service-specific dynamic config. Following is the default settings defined in
+notification message either shouldn't contain any information to allow user confirm the subscription, or it should contain a link that allows user to replace existing confirmed subscription with this one. You can customize duplicated subscription notification message by setting config *subscription.duplicatedSubscriptionNotification* in either *config.local.js* or using configuration api for service-specific dynamic config. Following is the default settings defined in
 *config.json*
 
 ```json
@@ -119,6 +119,24 @@ notification message doesn't and shouldn't contain any information to allow user
 }
 ```
 
+To allow user to replace existing confirmed subscription, set the message to something like 
+
+```json
+{
+  ...
+  "subscription": {
+    ...
+    "detectDuplicatedSubscription": false,
+    "duplicatedSubscriptionNotification": {
+      "email": {
+        "textBody": "A duplicated subscription was submitted. If the request is not submitted by you, please ignore this message. Otherwise if you want to replace existing subscription with this one, click {subscription_confirmation_url}&replace=true."
+      }
+    }
+  }
+}
+```
+The query parameter *&replace=true* following the token *{subscription_confirmation_url}* will cause existing subscription be replaced.
+
 ## Anonymous Unsubscription
 For anonymous subscription, *NotifyBC* supports one-click opt-out by allowing unsubscription URL provided in notifications. To thwart unauthorized unsubscription attempts, *NotifyBC* implemented and enabled by default two security measurements 
 
diff --git a/spec/app/subscription.spec.js b/spec/app/subscription.spec.js
index f2f4130..10419ac 100644
--- a/spec/app/subscription.spec.js
+++ b/spec/app/subscription.spec.js
@@ -476,11 +476,6 @@ describe('GET /subscriptions/{id}/verify', function() {
             userChannelId: 'bar@foo.com',
             state: 'unconfirmed',
             confirmationRequest: {
-              confirmationCodeRegex: '\\d{5}',
-              sendRequest: true,
-              from: 'no_reply@invlid.local',
-              subject: 'Subscription confirmation',
-              textBody: 'enter {confirmation_code} in this email',
               confirmationCode: '37688'
             }
           },
@@ -497,14 +492,21 @@ describe('GET /subscriptions/{id}/verify', function() {
             userChannelId: 'bar@foo.com',
             state: 'unconfirmed',
             confirmationRequest: {
-              confirmationCodeRegex: '\\d{5}',
-              sendRequest: true,
-              from: 'no_reply@invlid.local',
-              subject: 'Subscription confirmation',
-              textBody: 'enter {confirmation_code} in this email',
               confirmationCode: '37689'
-            },
-            unsubscriptionCode: '50032'
+            }
+          },
+          function(err, res) {
+            cb(err, res)
+          }
+        )
+      },
+      function(cb) {
+        app.models.Subscription.create(
+          {
+            serviceName: 'myService',
+            channel: 'email',
+            userChannelId: 'bar@foo.com',
+            state: 'confirmed'
           },
           function(err, res) {
             cb(err, res)
@@ -527,24 +529,33 @@ describe('GET /subscriptions/{id}/verify', function() {
   })
 
   it('should verify confirmation code sent by anonymous user', async function() {
-    let res = await request(app)
-      .get(
-        '/api/subscriptions/' + data[1].id + '/verify?confirmationCode=37689'
-      )
-      .set('Accept', 'application/json')
+    let res = await request(app).get(
+      '/api/subscriptions/' + data[1].id + '/verify?confirmationCode=37689'
+    )
     expect(res.statusCode).toBe(200)
     res = await app.models.Subscription.findById(data[1].id)
     expect(res.state).toBe('confirmed')
   })
 
   it('should deny incorrect confirmation code', async function() {
-    let res = await request(app)
-      .get('/api/subscriptions/' + data[1].id + '/verify?confirmationCode=0000')
-      .set('Accept', 'application/json')
+    let res = await request(app).get(
+      '/api/subscriptions/' + data[1].id + '/verify?confirmationCode=0000'
+    )
     expect(res.statusCode).toBe(403)
     res = await app.models.Subscription.findById(data[1].id)
     expect(res.state).toBe('unconfirmed')
   })
+
+  it('should unsubscribe existing subscriptions when replace paramter is supplied', async function() {
+    let res = await request(app).get(
+      '/api/subscriptions/' +
+        data[1].id +
+        '/verify?confirmationCode=37689&replace=true'
+    )
+    expect(res.statusCode).toBe(200)
+    res = await app.models.Subscription.findById(data[2].id)
+    expect(res.state).toBe('deleted')
+  })
 })
 
 describe('DELETE /subscriptions/{id}', function() {