It's really rare (maybe like once every few days), but I see duplicate entry errors show up in our server log once in awhile when someone tries to follow someone. Not really sure how to replicate it... I've tried double clicking follow really fast, etc. and I know there's code that checks if they are already following before it tries to follow them, but for whatever reason there's a case where that check fails when it shouldn't somehow. We aren't using any custom database adapter, no master/slave setup, no custom datawriters or models that would affect it. Maybe a good idea for it to be an INSERT IGNORE in this case?