To me this seems like a sync-detection issue in iOS8. I have never seen this issue in iOS7 and a second device, that still had iOS7 (migrated to iOS 8) did not show this evidence in iOS7, but in in iOS8 after synchronizing the first time again.
I noticed, that these doubles appear when removing sync'ing via iTunes, removing on the iOS device and re-downloading from the cloud. The problem afterwards is that unfinished downloads appear with dotted grey circles in the "on my device" view of the iDevice. The annoying thing is: you cant delete this entries, at least I cant. Wiping the whole library and re-synchronizing does not remove the duplicates in the iOS view.
However all of the "unfinished grey-dotted" entries appear as 128kbit stream entries, not the actual AAC 256Kbit ones.
This may indicate that these are stubs from iTunes Match - but I never had iTunes Match. 🙂
Calling Apple ended up in an Odyssee of a mixture of being puzzled, ignorant and inability to neither understand, nor solve the issue. At some point, the term "expected behaviour" even came up, where I can not understand this, unless Apple has re-invented the word "synchronization".
The entries are only duplicate on the device only - in synchronization view - not in the iTunes library, nor in my playlists/iOS sound library (at least normally not), unless I purchase something from the cloud, which I simultaneously also download to the iOS device, not just the iTunes Application on the PC. The next sync will greatly double all this. And best of this is, each duplicate has its own purchase date. 🙂
Apple, of course, has no clue so far, or at least it's the regional EMEA support, that is so "creative", trying out the most adventurous ways to keep the customer busy. That's my impression... Browsing the internet, there are many people facing these issues.
In the meantime, one album of mine had a quadruple representation of each of its songs. Amazing, isnt it? 3 times the stream-version entries with 3 different purchase dates, 1 the playable AAC. Honestly spoken, I believe Apple has broken something really bad for the icloud/iTunes Match integration and does not confirm it, because my iPhoto integration also seems to be a bit unstable sometimes.
According to the iTunes Store support, my account is clean, which i dont believe, of course after this triad. And after 3 months of making calls again and again it is really frustrating.
Somehow, after some observation, it seems that the synchronization process does not seem to recognize it's own same songs. The double entries, that cannot be deleted from the "on my device" view (files that are on the iDevice) in iTunes, even have different Genres sometimes.
So,if someone has an idea to "wipe" the itunes library on the device (not speaking about deleting the songs just,restart and resync, because I already did this), to start really fresh, without resetting the whole phone and build up everything from scratch (because Apple does not provide any solutions for this), or why the phone is replicating same entries with new purchase dates, let me know.
The point is, some friends have this issue, some do not, so it is by heaven NOT an expected feature. To me however, the AppleCare support for now is totally useless, so I guess the experts are more around in the forums, like here, not in their company.
If you have other details on this, kindly let me and/or others know.
Cheers
Hype