Sorry, I can't reproduce that. I started a new game with Factorio 1.1, went into the sandbox, built a belt loop, and saved while still in the sandbox (hitting escape to get to the menu for saving the game put me back on my original surface in Factorio 2.0). Then I loaded that saved game in Factorio 2.0, where I was immediately put back on my original surface and had my previous character.
If you are using SA, can you reproduce the error without it? If so, I'd like to get a copy of the saved game. If the error occurs only with SA (which I don't have), could you enable logging and send me factorio-current.log, if possible via PM in the forum?