Well if you grown before you should know whats up... First off you have got to transplant them into seperate pots, EACH. Second the only reason I can think of is not enough light so they are stretching... toward the light.

And they are probably kinda attacking eachother for nutrients since they are in the same pot. Honestly I think the roots might be tangled already. Your best bet is to TRY and transplant them seperatly or just yank 3 outa 4 out. Cause there is a very good chance they will die with shock in such a young state.

Hope it helped.