I traded my MW Danish GS for a MW German GS on the marketplace earlier today and all is fine, my Danish is gone and my new German has took it's place. The problem is my Danish AND my German show up in game, the last time this happened I left it alone as I thought it was a server update problem and would sort itself after a while. But eventually the trade actually reverted itself and I got my old Danish back, now I don't want this to happen again so I am posting here to make sure it won't.
Edit: It appears to have now fixed itself, but I shall post back if the trade reverts like last time.