i dont believe so, but I have to wonder why a group would offer a stipend so early. If you sign a contract, you'd better be sure you want to join them. You may change your mind about groups later.
If it's b/c the group you want to join is in the small town where you grew up but most people don't want to move ... that could be a good deal. if the group has recruiting problems that aren't b/c of the location ... be careful.
I know some people who have done it. Just make sure there is a fair clause to get out of it if you change your mind. You will most likely have to return the money and maybe some more.
I would not want to commit myself to any group this early in the game. Suppose you decide to do a fellowship. Are you single suppose your so wants to move. These people will own you. A part of the reasoning behind such arrangements is to lock you. What happens if you change your mind. How much do you pay them back. Also how long are you committed to these people.
I did something similar to this in another specialty. I got burned. I was tied down in a bad location.
Your program will not care about any contract that you sign if if does not interfere with your ability or availability to function as a resident in their program.
This kind of stuff is actually not uncommon. As mentioned above, many people from smaller cities know when they enter residency exactly where they wish to practice when they are done. Often, they know members of the group already. A stipend in that situation is a very nice bonus. As long as you have an out and know the group and the city well, I think it can be a very positive thing. Most that I know that have done this have not been secretive about it. How else would they explain the car they are driving that happens to be nicer than some of the attending's cars.🙂