Suggestion 4: Adding checks for newVal == oldVal

solidity/contracts/PausableOwnable.sol

@@ -35,6 +35,10 @@ abstract contract PausableOwnable is
     ///         mechanism.
     error PausableUnauthorizedAccount(address account);
 
+    /// @notice Reverts when the new pause admin address is the same as the
+    ///         current pause admin address.
+    error SamePauseAdmin();
+
     /// @notice Reverts if called by any account other than the pause admin
     ///         or the contract owner.
     modifier onlyPauseAdminOrOwner() {
@@ -95,6 +99,9 @@ abstract contract PausableOwnable is
         if (newPauseAdmin == address(0)) {
             revert ZeroAddress();
         }
+        if (newPauseAdmin == pauseAdmin) {
+            revert SamePauseAdmin();
+        }
 
         emit PauseAdminUpdated(newPauseAdmin, pauseAdmin);
 

solidity/contracts/stBTC.sol

@@ -74,6 +74,12 @@ contract stBTC is ERC4626Fees, PausableOwnable {
     /// Reverts if the address is disallowed.
     error DisallowedAddress();
 
+    /// Reverts if the treasury address is the same.
+    error SameTreasury();
+
+    /// Reverts if the dispatcher address is the same.
+    error SameDispatcher();
+
     /// @custom:oz-upgrades-unsafe-allow constructor
     constructor() {
         _disableInitializers();
@@ -104,6 +110,9 @@ contract stBTC is ERC4626Fees, PausableOwnable {
         if (newTreasury == address(this)) {
             revert DisallowedAddress();
         }
+        if (newTreasury == treasury) {
+            revert SameTreasury();
+        }
 
         emit TreasuryUpdated(treasury, newTreasury);
 
@@ -128,6 +137,9 @@ contract stBTC is ERC4626Fees, PausableOwnable {
         if (address(newDispatcher) == address(0)) {
             revert ZeroAddress();
         }
+        if (address(newDispatcher) == address(dispatcher)) {
+            revert SameDispatcher();
+        }
 
         address oldDispatcher = address(dispatcher);
 

solidity/test/stBTC.test.ts

@@ -1554,6 +1554,14 @@ describe("stBTC", () => {
         })
       })
 
+      context("when a new dispatcher is the same as the old one", () => {
+        it("should revert", async () => {
+          await expect(
+            stbtc.connect(governance).updateDispatcher(mezoAllocator),
+          ).to.be.revertedWithCustomError(stbtc, "SameDispatcher")
+        })
+      })
+
       context("when a new dispatcher is non-zero address", () => {
         let newDispatcher: string
         let stbtcAddress: string
@@ -1616,6 +1624,14 @@ describe("stBTC", () => {
         })
       })
 
+      context("when a new treasury is same as the old one", () => {
+        it("should revert", async () => {
+          await expect(
+            stbtc.connect(governance).updateTreasury(treasury),
+          ).to.be.revertedWithCustomError(stbtc, "SameTreasury")
+        })
+      })
+
       context("when a new treasury is Acre address", () => {
         it("should revert", async () => {
           await expect(
@@ -1693,6 +1709,16 @@ describe("stBTC", () => {
               .withArgs(pauseAdmin.address)
           })
         })
+
+        context("when updating pause admin to the same address", () => {
+          beforeAfterSnapshotWrapper()
+
+          it("should revert", async () => {
+            await expect(
+              stbtc.connect(governance).updatePauseAdmin(pauseAdmin.address),
+            ).to.be.revertedWithCustomError(stbtc, "SamePauseAdmin")
+          })
+        })
       })
 
       context("when the unauthorized account tries to pause contract", () => {