In my experience, the larger of the twins is generally a yearling buck. I can't recall the larger one ever being a doe.
I've hunted in some high deer population areas where they also have an earn a buck programs. If you want a buck (or multiple bucks), you have to kill one or more antlerless deer first. In some places with nice bucks, you have to kill one or more doe first before you are allowed to tag a buck. In situations like this, it turns into a scorched earth scenario. If its legal, it gets harvested. That is the intention of the DNR after all. They want the population reduced and are willing to force hunters to harvest doe first and frequently to earn the right to tag a buck.
Plus, my wife prefers to eat the smaller ones and they are a lot easier to drag.