I had 2 different games on different devices but I was told that I had to pick one. What happened to..

To be backed up, each game should have it's own Facebook account. But if you mix up the two Fb accounts on the 2 devices, the game will make you select only one of those games and will delete the other. If the game is not deleted, yet, log out of Fb on both devices. Then on the device that has not had an issue, log into Fb and start the game. In the game settings, go to "social", edit connections, and "log out". Then on the other device, log into 2nd Fb account and start the game. Hopefully the 2nd game will appear and you'll not have to select between your 2 games. Good luck.