Another male puppy addition

Question
We currently have a 5 month old male black lab puppy, who is well adjusted, well socialized, and doing brilliantly with his training. We would like to introduce another male large breed puppy around April next year (ours will be 11 months then). What sort of problems would you forsee, or can males live in harmony together if introduced in this way?  

Answer
Normally there isn't a problem.  It would be even less likely to be a problems if the second one was a female.  The big problem is if both have a strong drive for dominance.  Talk to the breeder and try to get one of them more submissive males from the litter for the second.  One the submitted to its litter mates should submit to the older one if it is dominating without any problem.