Constant mounting?

There's a 2 year old male castrated Lab the visits my local field, he mounts other males almost constantly and this morning took a liking to Barney, my Lab Puppy. Barney wasn't impressed and was getting quite stressed so I stuck him back on lead so I could keep the other dog off.

The Owner says it's dominance but I think most of us here would disagree with that so I just wondered if you have any ideas why a castrated male would behave like this.
He was already neutered when they got him at 6 months old.

If he has been allowed to do this behavior for over year then I guess it is pretty ingrained, I would say a poor training issue??? Samson is entire and is corrected if he ever tries this, but if they are excusing his behavior and allowing it then he will keep doing it. Just my take on it though

Worst dog for humping we had was entirely our fault, we thought at first it was funny and he just got away with it, by the time we thought not such a good idea he was pretty much fixed on thinking it the best thing since sliced bread and we had a heck of a time stopping him.

Next dog we said no straight away.

Wow, I can't believe that the dog was allowed to carry on and it was you who had to put Barney on the lead Humping is just bad manners and he should have been corrected from the beginning. All very well for the owner to glibbly say it's a dominance thing. Whatever it is, there is no excuse why the owner didn't stop him. Its a bit like a dog coming over to one of your and biting it and the owner just saying 'oh its a dominance thing'

Its normally due to being over excited when a dog gets too over whelmedx Hope that helps

Ollie was castrated at 6 months and the target of being humped which I believe is due to being one so young. He never humped a dog or person in his 41/2 years of life.

Dillon castrated almost two weeks ago 17 months never humped another dog but always trying it with humans mostly male. We stopped him every time but even with trying to train it out very difficult to stop him he got very over whelmed with his hormones. Sounds like the other dog should be the one on the lead not Barney.