AFAIK, for who use same exchange although they are 2 different people or just 1 people , they consider as 1 person and the other one is his/her alt.
That's forum stance !

About Digaran's case, let say if Nulius or other member who same level with his posting skill abusing his/her power by creating alts, it's possible to happen but in order to prove it happen, I think there are many member on this forum that able to identify the abuser or admin can see every people's IP address,right ?