Here's the entire log of sessions and shares: https://pastebin.com/s97g6ps9

You can see which shares are duplicated by the diff value. For example, share 19 is a duplicate of share 11, and share 229 is a duplicate of share 224, and so on

I can't work out what exactly causes them, but they always pop-up after the devfee and they are all a duplicate of some older sahre (not the immediately previous one).

Could you investigate and fix this?