Prevent players who have never logged in before from taking over existing accounts.

EssentialsGroupManager/src/Changelog.txt

@@ -229,4 +229,5 @@ v2.1:
 	- Add UUID support.
 	  Plugins can still query by player name but a UUID is faster and preferable.
 	- Set a default mirror map if none is found in the config.
-	- Fix clones forgetting sub groups.
+	- Fix clones forgetting sub groups.
+	- Prevent players who have never logged in before from taking over existing accounts.

EssentialsGroupManager/src/org/anjocaido/groupmanager/dataholder/WorldDataHolder.java

@@ -155,7 +155,7 @@ public class WorldDataHolder {
 		// Search for a LastName match
 		for (User usr : getUserList()) {
 			
-			if (usr.getLastName().equalsIgnoreCase(currentName)) {
+			if (usr.getLastName().equalsIgnoreCase(currentName) && !usr.getUUID().equalsIgnoreCase(usr.getLastName())) {
 				
 				// Clone this user so we can set it's uUID
 				user = usr.clone(uUID, currentName);