I had a weird problem occur as well. I was set as a superadmin from a long time ago, but when i went to look for the users.txt in the data/ulib/ folder it was not there. I proceeded to readd my user again to create a user.txt and superadmin was repeated twice. I was also given a allow tag of "ulx hasreadaccess". Is that even a valid command?
I can try and replicate this for you, but i am not sure how the user.txt can be removed and yet the admins still have power. I have looked duplicate users.txt and can not find them anywhere.