Board Thread:General Discussion/@comment-28424239-20160901211044/@comment-35284508-20180813183920

warning to people reading this post: MT does not recommend and will not support the same game on multiple devices. Each device has a different game ID code even if you are using the same name and avatar. They help with transferring parts of the game profile from one to another if requested but they will insist that you cease using the old device for that game. You can reinstall the game and start from level one as a different instance of the game - that seems ok with MT.

As far as recovering your ID code so you can have MT transfer your stuff to a new device, I'm not sure. If you gave your code to someone to establish a friendship that person may still have it in their notes. The multitude of people who have mentioned their code on this wiki, FB or some blog have a chance of finding their message again. It is clear from the messages above that FB might save part of your profile for you but probably does not have the code as part of that profile.