Oh my!! He's SO cute!!!!!
Definitely get him neutered. You'll have a better companion and avoid a lot of behavioral and health issues. We had an un-neutered (for a short time) dog when I was young and he marked everything and was always "on the make" (trying to get out when females in the neighborhood were in heat). There are also reproductive cancers of the testicles and prostate.
Probably they are just playing and trying to work out their rank, and I don't know if neutering will change the way they interact. I'm sure someone else can give you better information, but I thought I'd share my personal experience.