You can always manually edit license.file to remove unwanted licenses. If
you start LISTSERV with a 1.8c build, it will ignore 1.8b licenses as
they are not valid. If you start with a 1.8b build, both licenses are
eligible. You only need 1 more day on the 1.8b license to make LISTSERV
decide not to supersede it. There was also a missing test in some 1.8b
builds which caused some LAKs not to be superseded when they should have.
Eric