Well in the early war they were happy just to get them to go off at all.
It may have been a small concern but the methods use to fire pretty much eliminated any problem and I have never heard of any real concern by ships captains etc. In theory it could happen with a fast speed setting right behind a slow one or two torpedoes aimed very close to each other. Never heard of it happening though.
In the game it has no effect at all.
Magic