If you didn't have the carrying capacity, it would still duplicate and just leave it in his inventory.

At the moment (and in my experience as a fellow Necro) minions are just too weak to be much help in harder/higher content. There are only a small few builds I've seen where minions are viable, and they require very specific builds/items that would be hard to find at 40. Finding a build that sacrifices them is usually the better option. Although it's been nerfed heavily, the bone spear build is still very strong and is what I used to solo the capstone at 42 this season. Not sure if there's a difficulty difference running the capstone on wt1 or wt2, but if there is, my clear was wt2