Rodster,
We do have some code to check if the post that's about to made is *not* the same as the last post in your feed. Unfortunately, Facebook changes how they report the last post and it seems to be breaking that detection sometimes.
With that said though, disabling that feature is what we'd recommend. We're actually going to be (likely) removing that feature at some point over the next 6 months, because:
* Facebook recently revised their App Platform policies to state that any posts to a users wall must be approved by the user and/or have a user-editable message. The way we're doing it right now, that's not possible.
* It can get spammy, even if it's only posted once (definitely when it's repeated a lot). Some of our users use very, very promotional text in their messages, which gets the message deleted by the user and the app marked as spam even quicker than a simple "I just registered on..." type message. We'd like to protect our users a little more from that happening.
* Open Graph Actions are a ton better as they convey a message of how the user is interacting on your site. As we add more Open Graph Action support, we're hoping our users will move to that over the auto-post feature anyways as it's a much more socially engaging message for their friends.
We are evaluating other options for how to post to a wall on registration (not so much on login) so that the option is still there for admins, but also better in general.
Hope that helps explain, sorry for the issues, and thanks for your feedback,
Alex
Limit amount of posts to Facebook on auto login feature
