I use a couple of great tools from joeware.net to remove a SID from a users SID History. I had a problem where the wrong user was mapped over during a migration when we were colasping multiple domains into one.
The 2 tools I used from joeware were adfind and admod, both free.
adfind -h IT-DC01 -default -f sAMAccountName=jackuser sidhistory
This listed the current SID's in the history of the users account. After deciding which one I wanted to removie I used admod to remove it.
admod -b "CN=Jack User,OU=Employees,OU=People,DC=mydomain,DC=edu"
Sid Removed and now where ready to take that SID and add it to the correct user account.
admod -b "CN=Jackie User,OU=Employees,OU=People,DC=mydomain,DC=edu"
Note: I found out after this post that this option does not work with SIDHistory. You will need to use the VB Script or ADMT to migrate the sid from the source domain.