I would do time outs for humping. When they start humping separate them, and whoever did the humping gets put into an area of no fun. Start with 2 minutes, and boost it from there if they persist.

Most dogs will begin to realize that humping=no fun after a few weeks.

 

It's normal, and has nothing to do with dominance. It's just play/excitement. Just distract then with a toy, and don't worry about it.
Read the stickies at the top of the First time owner/ Training forums. They have a lot of good info. Get rid of having any notion about alpha/dominance stuff. It's been disproven. Do not do alpha rolls, or try to "dominate" your puppy. (I know you didn't ask specifically about this, but since you mentioned "dominance", I thought I would mention it, and suggest reading the stickies. You own a powerful breed that could be dangerous if you tried to do 'alpha"/"dominance" type training.

 

I would also look up "Littermate Syndrome". You definitely don't want that happening either.

 

Never thought about littermate syndrome, haha. I've raised puppies before but not two at a time and not of such a huge breed. They are both male, will they get more aggressive about it before the 6 month "fixing" date? Thank you all kindly!

 

I don't know that they will get aggressive, but I think 6 months is a bit young to neuter a large breed dog. The hormones and chemicals from their testes aid a lot in the growing process. I would wait until they are at least 1-2 years old.