For rabbits or what?

The age isnt the issue, its the bad habbits of the dog.

I would take the 1.5 and work with it to see if it would hunt. Seems like he is still impressionable. Who knows about the 2 yr old, it may or may not be able to change. Give it a shot.

You may be able to fix that 2 yr old with breaking scents, use rabbit scentand an e-collar. Train him to trail deer or something. Just not rabbits.