I’ll forward this by saying I didn’t take any screenshots of it happening, and making it happen again is going to be a super rare thing but may as well list it here in case anyone else comes across it, because it basically bricked my hand and it was lucky the game was over in the next two rounds.
Playing a highlander dragon deck I added Avinia to it after the changes, cause randomness is fun. I drew a spirit of the badlands and got the Mirage card from it since I did start with a highlander deck and it still worked. After a turn the mirage turned into a 1 mana Ysera that Anivia must have also summoned into the deck. I played the 1 mana mirage and the mirage turned purple but then doubled on itself., there was a purple one stuck as Ysera filling my hand and a blue one superimposed over it, I couldn’t select either but they were taking up hand slots. I don’t know if this interaction is because it copied a creature that was never in my deck with an ‘incorrect’ mana cost but I’m unsure.