I see this bug too and I see it on more than on moonkins.
The Picture say's everything, but maybe I should translate.
On the first picture you see a friend of mine playing a mage. The Talentspec says that the she is skilled as tank.
On the second one you see a shaman I never seen before. The talentspec says he has a holy talent skill.
So What I think is, that nUI mix the talentspec's of the players of an raid, because the priest under the shaman was skilled as Holy. The Warrior with name Crarbag on the screen is skilled as tank and the Paladin on the first place in the group too.
What I watched several times with nUI5 and 6 is that if click right on a char and want to look on the talents, mostly they are changing after a second or so, to a shaman talent tree, equally which char I want to see. Only shamans I can look without many Problems.
I'll tanke a look deeper if there is an addon conflict, but with nUI6 this problem is going back really hard. with nUI5 it works most of the times, with nUI6 never.