diff --git a/Jumoo.uSync.Core/Serializers/ContentTypeBaseSerializer.cs b/Jumoo.uSync.Core/Serializers/ContentTypeBaseSerializer.cs
index 7b54e343..845008fa 100644
--- a/Jumoo.uSync.Core/Serializers/ContentTypeBaseSerializer.cs
+++ b/Jumoo.uSync.Core/Serializers/ContentTypeBaseSerializer.cs
@@ -20,7 +20,14 @@ abstract public class ContentTypeBaseSerializer<T> : SyncBaseSerializer<T>, ISyn
         internal IContentTypeService _contentTypeService;
         internal IDataTypeService _dataTypeService;
         internal IMemberTypeService _memberTypeService;
-        internal IEntityService _entityService; 
+        internal IEntityService _entityService;
+
+        // all content/media cached lists - they are used when 
+        // creating new properties to make sure we don't YSOD the site.
+        // 
+        private List<IContentType> _allContentTypes;
+        private List<IMediaType> _allMediaTypes;
+
 
         public ContentTypeBaseSerializer(string itemType): base(itemType)
         {
@@ -138,8 +145,13 @@ internal void DeserializeStructure(IContentTypeBase item, XElement node)
             item.AllowedContentTypes = allowedTypes;
         }
 
-        internal void DeserializeProperties(IContentTypeBase item, XElement node)
+        internal string DeserializeProperties(IContentTypeBase item, XElement node)
         {
+            string message = ""; 
+            // clear our type cache, we use it to check for clashes in compistions.
+            _allMediaTypes = null;
+            _allContentTypes = null;
+
             List<string> propertiesToRemove = new List<string>();
             Dictionary<string, string> propertiesToMove = new Dictionary<string, string>();
             Dictionary<PropertyGroup, string> tabsToBlank = new Dictionary<PropertyGroup, string>();
@@ -191,10 +203,20 @@ internal void DeserializeProperties(IContentTypeBase item, XElement node)
 
                     if (property == null)
                     {
-                        // create the property
-                        LogHelper.Debug<Events>("Creating new Property: {0} {1}", ()=> item.Alias,  ()=> alias);
-                        property = new PropertyType(dataTypeDefinition, alias);
-                        newProperty = true;
+                        // for doctypes we need to check the compositions, we cant create a property here
+                        // that exists further down the composition tree. 
+                        
+                        if (CanCreateProperty(item, alias))
+                        {
+                            LogHelper.Debug<Events>("Creating new Property: {0} {1}", () => item.Alias, () => alias);
+                            property = new PropertyType(dataTypeDefinition, alias);
+                            newProperty = true;
+                        }
+                        else
+                        {
+                            message = string.Format("Property: {0} was not created because of clash (try running import again)", alias);
+                        }
+
                     }
 
                     if (property != null)
@@ -353,6 +375,8 @@ internal void DeserializeProperties(IContentTypeBase item, XElement node)
                 }
             }
 
+            return message; 
+
         }
 
         internal void DeserializeTabSortOrder(IContentTypeBase item, XElement node)
@@ -616,6 +640,42 @@ private IContentTypeBase LookupByAlias(string alias)
 
             return item;
         }
+
+
+        /// <summary>
+        ///  does a check to see that no doctype/media type below 
+        ///  what we are looking at has the property we want to 
+        ///  create, if it doesn, we warn and carry on. a double
+        ///  import fixes this 
+        /// </summary>
+        /// <param name="alias"></param>
+        /// <returns></returns>
+        private bool CanCreateProperty(IContentTypeBase item, string alias)
+        {
+            bool canCreate = true;
+
+            switch (_itemType)
+            {
+                case Constants.Packaging.DocumentTypeNodeName:
+                    if (_allContentTypes == null)
+                        _allContentTypes = _contentTypeService.GetAllContentTypes().ToList();
+
+                    var allProperties = _allContentTypes.Where(x => x.ContentTypeComposition.Any(y => y.Id == item.Id)).Select(x => x.PropertyTypes);
+                    if (allProperties.Any(x => x.Any(y => y.Alias == alias)))
+                        canCreate = false;
+                    break;
+                case "MediaType":
+                    if (_allMediaTypes == null)
+                        _allMediaTypes = _contentTypeService.GetAllMediaTypes().ToList();
+
+                    var allMediaProperties = _allMediaTypes.Where(x => x.ContentTypeComposition.Any(y => y.Id == item.Id)).Select(x => x.PropertyTypes);
+                    if (allMediaProperties.Any(x => x.Any(y => y.Alias == alias)))
+                        canCreate = false;
+                    break;
+            }
+            return canCreate;
+
+        }
         #endregion
 
     }
diff --git a/Jumoo.uSync.Core/Serializers/ContentTypeSerializer.cs b/Jumoo.uSync.Core/Serializers/ContentTypeSerializer.cs
index 2cf469f6..a72bdb37 100644
--- a/Jumoo.uSync.Core/Serializers/ContentTypeSerializer.cs
+++ b/Jumoo.uSync.Core/Serializers/ContentTypeSerializer.cs
@@ -112,7 +112,7 @@ internal override SyncAttempt<IContentType> DeserializeCore(XElement node)
             // _contentTypeService.Save(item);
 
             // Update Properties
-            DeserializeProperties((IContentTypeBase)item, node);
+            var msg = DeserializeProperties((IContentTypeBase)item, node);
 
             // Update Tabs
             DeserializeTabSortOrder((IContentTypeBase)item, node);
@@ -143,7 +143,7 @@ internal override SyncAttempt<IContentType> DeserializeCore(XElement node)
             // structure twice.
             // DeserializeStructure((IContentTypeBase)item, node);
 
-            return SyncAttempt<IContentType>.Succeed(item.Name, item, ChangeType.Import);
+            return SyncAttempt<IContentType>.Succeed(item.Name, item, ChangeType.Import, msg);
         }
 
         private int GetContentFolders(XElement info, IContentType item)
diff --git a/Jumoo.uSync.Core/Serializers/MediaTypeSerializer.cs b/Jumoo.uSync.Core/Serializers/MediaTypeSerializer.cs
index f3600d0f..62a2552f 100644
--- a/Jumoo.uSync.Core/Serializers/MediaTypeSerializer.cs
+++ b/Jumoo.uSync.Core/Serializers/MediaTypeSerializer.cs
@@ -94,7 +94,7 @@ internal override SyncAttempt<IMediaType> DeserializeCore(XElement node)
                 item.SetLazyParentId(new Lazy<int>(() => parentId));
             }
 
-            DeserializeProperties(item, node);
+            var msg = DeserializeProperties(item, node);
 
             DeserializeTabSortOrder(item, node);
 
@@ -103,7 +103,7 @@ internal override SyncAttempt<IMediaType> DeserializeCore(XElement node)
 
             _contentTypeService.Save(item);
 
-            return SyncAttempt<IMediaType>.Succeed(item.Name, item, ChangeType.Import);          
+            return SyncAttempt<IMediaType>.Succeed(item.Name, item, ChangeType.Import, msg);          
         }
 
         private int GetMediaFolders(XElement info, IMediaType item)
diff --git a/Jumoo.uSync.Core/Serializers/MemberTypeSerializer.cs b/Jumoo.uSync.Core/Serializers/MemberTypeSerializer.cs
index 54b529c0..3cc7161d 100644
--- a/Jumoo.uSync.Core/Serializers/MemberTypeSerializer.cs
+++ b/Jumoo.uSync.Core/Serializers/MemberTypeSerializer.cs
@@ -58,13 +58,13 @@ internal override SyncAttempt<IMemberType> DeserializeCore(XElement node)
 
             DeserializeBase(item, info);
 
-            DeserializeProperties(item, node);
+            var msg = DeserializeProperties(item, node);
 
             DeserializeTabSortOrder(item, node);
 
             _memberTypeService.Save(item);
 
-            return SyncAttempt<IMemberType>.Succeed(item.Name, item, ChangeType.Import);
+            return SyncAttempt<IMemberType>.Succeed(item.Name, item, ChangeType.Import, msg);
         }
 
         internal override SyncAttempt<XElement> SerializeCore(IMemberType item)
diff --git a/umbPackage/uSync.BackOffice/Jumoo.uSync.Core.dll b/umbPackage/uSync.BackOffice/Jumoo.uSync.Core.dll
index 9c4ec079..b40f6763 100644
Binary files a/umbPackage/uSync.BackOffice/Jumoo.uSync.Core.dll and b/umbPackage/uSync.BackOffice/Jumoo.uSync.Core.dll differ
diff --git a/umbPackage/uSync.Core/Jumoo.uSync.Core.dll b/umbPackage/uSync.Core/Jumoo.uSync.Core.dll
index 9c4ec079..b40f6763 100644
Binary files a/umbPackage/uSync.Core/Jumoo.uSync.Core.dll and b/umbPackage/uSync.Core/Jumoo.uSync.Core.dll differ