learjet,
We actually have a code check in JFBConnect that should prevent the same message being posted to the user's wall if that's also their last message. So, there really shouldn't be duplicate repeated posts... so if you're seeing that, that doesn't seem right.
As for a developer only mode, it's not a bad idea. For development, we actually have a couple Facebook accounts and don't user our 'personal' accounts for test purposes for just that reason. You may want to consider creating a new Facebook account just for testing purposes. Facebook doesn't want lots of extra accounts for users, and there are ways to create "Test Users". We haven't worked with the "Test User" functionality much, but it may also be something for you to look into.
Hope that helps, and let us know if duplicates are being posted without other status messages showing in between.
Thanks,
Alex
Facebook Wall Spam
