I am also having the Overwrite issue. Yes, it's definitely a cache thing.
I uploaded some files, but in the Scene List and Play Through, it still shows the old ones. But, when I play test on my iPad, it's up to date.
So, I completely cleared my Cache and it works fine now.
Problem is: I'm Beta Testing. How can I be certain that my beta testers aren't using old cached files?
Also, at work I can clear my cache with no real worries, but, sometimes you don't want to dump your entire cache.
Is this an issue that can be fixed? Is this occurring a lot, or was this just a rare issue that may not occur again?