Regularly the messages in some subfolders are doubled. I don't know why or how it was triggered. It is very annoying, because some subfolders contain a lot of messages. Since I don't know how to get rid of this double messages, except by deleting them by hand one at the time, it is a very time consuming matter. I tried repairing the folder, but that didn't work. I already have had a folder where all messages were doubled several times. So every message was there six, seven, or eight times! Is there somebody with an explanation and - preferably - a solution to prevent this?