SSAS: Administrator role is not really admin!

I discovered this week an interesting bug in SSAS (both 2005 and 2008 versions). A user that was supposed to have full permission complained he can see only few members in a dimension. I checked his role and it really was defined as "Full control (Administrator)" (Checkbox in General tab of role properties). After short investigation I found that this role was in past with those limitations in members, and later the admin checkbox was selected to make this user admin on DB.