I’m tagging @wkaj @superpig @Tomas1856 as they took part in this thread from way back which I have insufficient privileges to post to.
It’s the problem where you get a new file created with a ’ 1’ appended to the name and the file you’re trying to replace remains. I’ve been getting it quite a bit when updating third-party plugins since moving to Unity 5. Most recently when updating the Facebook plugin from 7.1.0 to 7.2.0 - loads of files inside the iOS Facebook frameworks got duplicated.
I got this response from Unity QA which seems to imply that it’s just the way it works now.
“We have got a word from our Developers, that we have changed the way on how Unity identifies assets. Old way was that if the asset had same path, but different GUID, we would replace that asset and it would get a new GUID. But now we have changed this and Unity will identify assets only from GUID. It means, that in your attached project, that package you want to import has “EgoXproject.dll” with different GUID. That is why it creates a new file in same path, but with different name, instead of overwriting old one.”
But Mike at Prime31 seems to think it is something that is going to be fixed.