Not sure what to tell you, because I cannot even fathom how this could happen. I assume when you say "all the names appeared twice", you are referring to the database. The only way for this to happen is if the td.db file was manually modified, and that would not be an easy thing to do. It couldn't possibly happen "by accident".
Now, if you "moved all of your data", and then loaded a tournament and noticed the players were not in the database (indicated by the fact that the player names, on the Players tab, were italicized), and press Add All to DB, then this could happen, but only if you first manually added all of the players that WERE in your database into the new database. In other words, you moved everything but perhaps didn't properly move the database, noticed the database was empty, added all of your players (manually), then used the Add All to DB feature on the Players tab to add all the players from a tournament into the database.
Frankly, I'd start over and follow the instructions in the user manual for backing up and restoring your data. I've got an item on the to list to add a Restore feature to make this less prone to human error. But for now, if you follow the instructions in the user manual, it should work fine.
