I saved with a Bad Egg in my party and updated, and I can both dupe and freely trade online. Instead of doing the needful and fixing the glitch itself with the Bad Egg, they only fixed the glitch to GET the Bad Egg. As long as you still have one in your party, duping works exactly as it did pre-update.
Downside is that I'm just stuck with a Bad Egg in my party. I'm not tore up about it because I'm mostly finished with the game, but a lot of people are saying saving with a Bad Egg in your party is a bad idea that could brick your shit. However while playing with the duplication glitch over several points in my game save, I would save with a Bad Egg and have it in my party for a bit. Nothing happened so I'm wondering if the fatal glitches are more if you do stuff like join the Hall of Fame or something else while having the Bad Egg in your party.