[Christopher]

Yes, they are repeating actions (as far as the duplicates are concerned). To my knowledge, I've only been completing them on one or the other device before syncing. Will it happen for all repeating tasks regardless?

It's possible that I've run into the sync issue with the iPhone going to sleep. I'll try to be more diligent in watching for that. I've only had a few instances of completing an action on the iPhone and it not showing up on the desktop - and those have not been repeating actions.