FWIW, I have several hollies with similar trunks. I believe they got that way after being cut way back following hard winter diebacks. This doesn't answer your question as to whether it is an inferior trunk. I'll be interested to know.

If you plan to trim them into a shrub form indefinitely, this probably doesn't matter. If you plan for them to grow as specimen trees - one has a choice with many cultivars of Holly - I myself, at least, would consider it very detrimental to their form.

But, FWIW, if you paid a lot of money for these from a "reputable nursery", it's enough of a flaw that in my opinion, you are justified asking for a replacement. I certainly would not have picked this one for my garden, if I had a choice of better shaped ones. If they are correctly pruned in the nursery field, there is no reason for them to end up looking like this.

cf: https://www.houzz.com/discussions/we-agree-some-cutting-grown-trees-need-aggressive-waterspout-control-dsvw-vd~4977109

David, thanks, that’s very helpful. What form will a multi trunk tree like this take if it’s left unpruned over years? Will vertical growth be seriously inhibited a lot because it’s pushing up multiple stems ?

I don’t intend to have a pruned hedge, but I also don’t need “specimens.” It’s basically a backdrop with four Hollys, 10 feet apart. In many years, they’ll grow together, but their independent shape will be apparent for a while. If they take on an ellipsoidal shape, as NS usually do, that’s OK. I had planned to remove crossing inner branches, but otherwise not much. At the moment, they’re pruned like Christmas trees, but I assume that won’t last.

I honestly don't know. Hollies are overall pretty darn indestructible - my overall thinking it they will eventually fuse and the plant will be ok, it will always be an ugly warty and wavy shaped trunk compared to the straight, silvery bole of a healthy normal holly. Which is what I would want...

But I don't really know...it's not something I have to think about with my own holly collection because I'd never let the problem get to that point in the first place.

Dave in NoVA?

Thanks. Indestructible sounds good. The appearance of the trunk isn’t too much of an issue here, because it will be hidden by the foliage.