Not a good idea at all! How on earth do you think that you can line these planes up perfectly in the first place? You may make them to that they are both facing the same way before take off but do you really think they are going to go exactly straight or both turn exactly the same way at exactly the same time.

A minute difference will quickly add up to a big one and then you will find yourself trying to fly 2 separate planes on 1 transmitter. Sounds pretty dangerous to me!

Also remember that you will never be able to build 2 planes EXACTLY the same. They would both need individual trim and you simply cant do that if trimming one plane is going to set the other off.