How much time have you spent working with each puppy individually? What you are describing is a textbook case of what is known (anecdotally) as 'littermate syndrome'. It tends to happen when two littermates, or otherwise similarly aged puppies, are raised together without having the majority of their time spent apart. They end up bonding more strongly with each other than with their humans, which can cause behavioral problems (especially when social/sexual maturity hits, which is exactly where your boys are now). Going to 'daycare' could be exacerbating your issues, as it leads to entire days of overstimulation for both puppies. Are they altered? If not, that will further exacerbate the problems you're facing here. (Not that neutering is a magical wand that will eliminate behavioral problems, but, in this case, being intact could be a contributing factor)
My suggestion? Separate the two dogs. Work with each one as an individual. Separate walks. Separate daily training. Spend more time working on settling exercises such as Karen Overall's Relaxation Protocol, and less time walking/playing/physically exercising them. IF (and that's a big 'if') they continue to go to daycare, make absolutely they are NOT in the same group. Alternate days, so when one is at daycare, the other one is home for you to work with as an individual.
Honestly, my first suggestion would be to return one of them to the breeder (or otherwise rehome, if the breeder is unable/unwilling to take him back. It happens with less than stellar breeders, which I suspect these boys came from, since NO experienced & reputable breeder would sell two same sex puppies to an inexperienced home) and concentrate your efforts on the one remaining puppy. In another year or two, you can consider adding another pup to your family mix, but these two, right now? Not a good situation.
I'm sorry if these things are not what you want to hear...