for the dog or the owner?
Seriously your problem is complex. Its very difficult to unteach a dog a behavoir it was bred to do - after its learn to do it.
Your best bet is to keep trying the bark collars [what type do you have?] and teaching them that it is unacceptable behavior while you're around. [It'll be down right impossible to teach them that its a no no when you're not there].
First start them back at square one with obedience training
daily come, sit, stay, heel, down so that they do it automatically. Believe you me, a good lesson in obedience can do wonders for a pet. IF done consistantly they'll look at you as if you're a God wagging their tails...yea, yea, he said sit, I'm sitting, aren't I a good boy.
Next when ever they start to bark at all flip them on their backs, stare into their eyes, point your finger and say NO and hold them there for a long second or two.
Lastly, it might be wisest not to let them both out at once. Dogs in a pack [albeit small pack] are more prone to these things.
Good luck, Patty