Merging requesters and linking requests

I wonder if someone can help me. It would seem on our system our domain(AD) has been added twice, once with the full domain name and once with the netbios/shorterned domain name e.g. a typical requester will appear linked to uk.domain.name as well as just uk. We want to merge these two so we only have the single requester but we also want the requests that may of been logged under the one we're getting rid of to be linked to their name sake under the other.

Is this possible - as we do not want duplicates of all our requesters. We also have a number of requesters not associated with our domain that we wish to keep also.

Basically we want to enable the self service portal but with each requester having two names on the system this makes it slightly complicated.

Thanks.

Daniel