Un de-syncable songs

Hello there,

Ever since I updated my iPod Touch 5th gen to iOS8 (now on iOS9), I have "ghost" songs in my music library on the device.

Typically, they're playable only when I'm connected to wi-fi and grayed out the rest of the time, they're duplicates of songs I already have in my library or songs that I used to have but chose to un-tick in iTunes so that they don't sync anymore.

The "ghost" songs won't let me delete them on the device either and they don't appear twice in my iTunes library.

I think I had this problem before iOS 8 but disabling "show all music" in the settings corrected it.

This options no longer exists and the ghosts are back.

They're really annoying because every time they play in random mode it skips automatically and breaks my current playlist and when I'm actually connected to the internet, songs I de-synced still play.

I don't manually copy songs to my iPod and I don't use iCloud at all.

I tried de-syncing all music and re-syncing and until I reconnected to the wifi, the grayed-out duplicates were back (the duplicates inexplicably seem to have merged later and the unwanted ones are still there).

If it's any indication of what is going on, I looked at the music in the "on my device" tab and the duplicates/unwanted songs show up like this, with the weird circle logo :

On this screeshot, we can see "Hold on be strong" and "Nathaniel" are duplicates of songs I've since removed and others are just duplicates.

Thanks in advance for your help with getting rid of these.