Is This A Normal Thing?

We Have A 13 Year Old Neutered Dog. (part Beagle/german Shepered) He's Been The Only Dog For 13 Years. Recently We Got A New Boxer/pit Bull Mix Whos 3 Months Old. He Isn't Neutered And Everyday All Day The Older Dog Licks Him And Humps Him. I Know Its Common For Female Dogs To Possible Lick A Male/female Puppy But I Find A 13 Year Old Male Dog Not Normal Doing That To A Male Puppy. Often Times If The Puppy Isn't Interested And Doesn't Want To Be Bothered Jack Will Almost Run Him Over To Lick Max. Now He Looks Like He's Got A Rash From Were Jack Has Continuslly Licked Him. Is There A Scent The Puppy Has, To Make Jack Want To Do This Or Is It A Dominate Thing? It Is Very Gross And Annoying To Always Have To Yell At Him To Quit It. My Mom Says That They're Just Being Dogs But I've Never Heard Of Males Acting That Way And I Disagree With Her. Any Suggestions On What Makes Jack Do This Will Be Appreciated.

Sounds mostly like a dominance issue. New puppy means that the pack dynamic has been changed and Jack is making sure no one is questioning him being dominate over the new pup. I personally would try to curb this behavior by always being present when they are together and seperating them when you aren't around. If this continues as your new dog matures he will most likely challenge Jack and that could end very badly. Now is the time to make sure that Jack understands that YOU are alpha and you pick who gets to mount whom and that Jack mounting Max is not acceptable.

I am sure someone else will have a better plan for you but that is what I would start with.

Edited to add: German Shepherds and Pit Bulls are both dog aggressive breeds, you will need to work with them closely since they are both males to ensure they can co-exsist peacfully.