hi bro
from my little knowledge this problem may be have been happened because one of tow reasons
1- there is an actual computer holding the same name of the domain
so in this case u have to find this computer and rename it because it will cause a problems to ur network
u can search for it by using the active directory users and computers program to search the the computers
2- there may be a virus or worm in ur network duplicating computers names so u should start thinking about good antivirus or antiworm
hope i could helped
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