Its the time of year. Its mating time so male on male will need to settle who's top dog. If your introducing females he may wish to induct her into the harem but seriously. Unless you have adequate space as rule only one male will probably breed and any other males being subordinate*(unpartnered). This means also that with multiple litters from the one breeder they will generally have been sired by the one male.
As with all rules there are exception
So to introduce him successfully you can create enough space, create a new hide, totally change and clean the enclosure, wait till after breeding season or start another enclosure.
Cheers
Peter
ps. these are my opinions. I think that they are right but I am willing to be enlightened.