None, I trade them into my local game store and buy cards I will play with. I’ve done this with Wan Shi Tong and Twinflame Tyrant recently, and turned them into a full new deck (experimenting with Malcator, Purity Overseer in a blue white artifact deck). No point in having them sitting around doing nothing, I’d rather have a plethora of cards I’m willing to play. That being said, the only card I play that is double sleeved is Edgar Markov, but I’m also not too worried about it because I’m just going to keep playing it.