diff --git a/set-definitions/src/main/java/eu/europeana/set/definitions/model/UserSet.java b/set-definitions/src/main/java/eu/europeana/set/definitions/model/UserSet.java
index 7394b2a4..eb942b0c 100644
--- a/set-definitions/src/main/java/eu/europeana/set/definitions/model/UserSet.java
+++ b/set-definitions/src/main/java/eu/europeana/set/definitions/model/UserSet.java
@@ -97,4 +97,6 @@ public interface UserSet extends PageInfo {
     void setProvider(Provider provider);
 
     Provider getProvider();
+
+    boolean hasItem(String itemId);
 }
\ No newline at end of file
diff --git a/set-mongo/src/main/java/eu/europeana/set/mongo/model/PersistentUserSetImpl.java b/set-mongo/src/main/java/eu/europeana/set/mongo/model/PersistentUserSetImpl.java
index 3c464eb2..4c384de6 100644
--- a/set-mongo/src/main/java/eu/europeana/set/mongo/model/PersistentUserSetImpl.java
+++ b/set-mongo/src/main/java/eu/europeana/set/mongo/model/PersistentUserSetImpl.java
@@ -74,4 +74,9 @@ public String toString() {
 	public void setBaseUrl(String baseUrl) {
 	    //used only for web userset	    
 	}
+
+  @Override
+  public boolean hasItem(String itemId) {
+    return getItems() != null && getItems().contains(itemId); 
+  }
 }
\ No newline at end of file
diff --git a/set-web/src/main/java/eu/europeana/set/web/service/UserSetService.java b/set-web/src/main/java/eu/europeana/set/web/service/UserSetService.java
index d150302c..e7a79b44 100644
--- a/set-web/src/main/java/eu/europeana/set/web/service/UserSetService.java
+++ b/set-web/src/main/java/eu/europeana/set/web/service/UserSetService.java
@@ -255,4 +255,6 @@ ItemIdsResultPage buildItemIdsResultsPage(String setId, List<String> itemIds, in
      */
     UserSet publishUnpublishUserSet(String userSetId, Date issued, Authentication authentication, boolean publish) throws HttpException;
 
+    void validateCollectionSize(UserSet webUserSet, int newItems) throws ItemValidationException;
+
 }
\ No newline at end of file
diff --git a/set-web/src/main/java/eu/europeana/set/web/service/controller/jsonld/WebUserSetRest.java b/set-web/src/main/java/eu/europeana/set/web/service/controller/jsonld/WebUserSetRest.java
index 90f787fb..b32ea3c9 100644
--- a/set-web/src/main/java/eu/europeana/set/web/service/controller/jsonld/WebUserSetRest.java
+++ b/set-web/src/main/java/eu/europeana/set/web/service/controller/jsonld/WebUserSetRest.java
@@ -479,6 +479,7 @@ protected ResponseEntity<String> insertItemIntoUserSet(HttpServletRequest reques
       String eTagOrigin =
           generateETag(existingUserSet.getModified(), WebFields.FORMAT_JSONLD, getApiVersion());
       checkIfMatchHeader(eTagOrigin, request);
+      
       UserSet updatedUserSet =
           getUserSetService().insertItem(datasetId, localId, position, existingUserSet);
       
diff --git a/set-web/src/main/java/eu/europeana/set/web/service/impl/BaseUserSetServiceImpl.java b/set-web/src/main/java/eu/europeana/set/web/service/impl/BaseUserSetServiceImpl.java
index 1f0b89d5..a4d09ed0 100644
--- a/set-web/src/main/java/eu/europeana/set/web/service/impl/BaseUserSetServiceImpl.java
+++ b/set-web/src/main/java/eu/europeana/set/web/service/impl/BaseUserSetServiceImpl.java
@@ -591,6 +591,7 @@ public void validateWebUserSet(UserSet webUserSet, boolean isAlreadyPublished) t
     validateItems(webUserSet.getItems());
   }
 
+  @Override
   public void validateCollectionSize(UserSet webUserSet, int newItems) throws ItemValidationException {
     final int collectionMaxSize = getConfiguration().getCollectionMaxSize();
     if(webUserSet.isCollection() 
diff --git a/set-web/src/main/java/eu/europeana/set/web/service/impl/UserSetServiceImpl.java b/set-web/src/main/java/eu/europeana/set/web/service/impl/UserSetServiceImpl.java
index 3e95b79e..3167e2ed 100644
--- a/set-web/src/main/java/eu/europeana/set/web/service/impl/UserSetServiceImpl.java
+++ b/set-web/src/main/java/eu/europeana/set/web/service/impl/UserSetServiceImpl.java
@@ -239,10 +239,13 @@ public UserSet insertItem(String datasetId, String localId, String position,
     String itemForPartialValidation = "/" + datasetId + "/" + localId;
     validateItemPartial(itemForPartialValidation);
 
-    //check max number of items for the sets of type Collection
-    validateCollectionSize(existingUserSet, 1);
     String newItem =
         UserSetUtils.buildItemUrl(getConfiguration().getItemDataEndpoint(), datasetId, localId);
+    
+    //check max number of items for the sets of type Collection
+    if(existingUserSet.isCollection() && !existingUserSet.hasItem(newItem)) {
+      validateCollectionSize(existingUserSet, 1);  
+    }
 
     // check if the position is "pin" and is a EntityBestItem set then
     // insert the item at the 0 position