This is not a case of clear cheating, but it is irritating. I played JBond who has a low number of games and had a 774 ranking. I know that duplicate accounts have been mentioned many times before, but it is irritating, especially when they are not declared.
Secondly, I got disconnected in the middle of the game and he wouldn't share what pieces he had lost. He responded on chat later about something else (saying I got lucky when I killed many of his pieces with a lieutenant) so I know he was seeing the chat. Not really cheating but bad sportsmanship. I do wish Jumbo could fix this glitch. I had completely forgotten much of the pieces that I had taken and it probably cost me the game.
I wish I could say there were some remedy against duplicate accounts here. Or proudly that they are forbidden. Alas.
As for an opponent not helping you out in that situation it's pretty much poor sportsmanship, I agree, but probably not usually enforceable arising when it does from a BattleChat conversation due to language issues inherent in our multilingual site.
I can tell you on the glitch part itself that this was the also the case in the new app when it first began, but as far as I can tell it's been fixed there. I've lost connection a few times since, and have not lost my graveyards in a long while now.
They are simply not putting the effort into current web version any more. Sadly.