Hi there;

My keep doesn't really have split sessions, but I know human boxers (MMA fighters, etc.) train like this, so I don't think it would be a problem to do so for dogs.

It might even be an optimal way to train. Perhaps, say for example, a strength training workout in the AM, and an endurance/reflexes workout in the PM (or visa versa), etc.

Certainly, I don't think you would hurt your dog doing this, and it may ultimately prove to be the way to go.

Jack