They definitely look like Marco nocks to me. After having issues with the Bohning classic nocks that seems to be the standard for everything for some reason, I bought a small pack of every glue on nock I could find. Bohning T, AAE, Marco, Pro nock, and probably more. Why Bohning is as popular as it is I can't figure out why. More than once I've broken them just handling them. They are super thin, and made of the most brittle plastic. Pro nocks are what Bohning nocks want to be. They have the same design where the string never really snaps on. The difference is pro nocks have a stronger body, and the plastic isn't brittle at all. I don't remember much about the AAE. Marco nocks seem like the obvious choice. When you handle a Bohning and Marco side by side you will have that moment where you are amazed how much stronger the Marco is. The design of them also snaps on your string, which seems a much better way to go to me. Maybe snapping on the string isn't a good thing being the string angle changes during the draw and firing, but it doesn't seem to be the case in the real world. I'd rather my string stay all the way in the throat, vs Bohning/pro nock which often has a tiny little gap at full draw.
Yeah, I really got into some nitty-gritty arrow development this summer. Seasons here and deer are running around. Its time to make it happen.