Error when reassigning categories in Outlook 2003

I discovered that some contacts appeared in two categories (Master category
List) when only assigned to one category. Outlook 2003. I have a category
called Band and a second category called Unassigned which I use for former
band members and people no longer asisgned to a category but whose info I
dont' want to loose. I made a new category called Band No More and then
changed each of those unassigned band members to that new category. However,
they appeared in the current Band category as well, even though each
unassigned person was not assigned to the band category, only the Band No
More category.

I fixed the problem by reassigning all the "Band No More" people back to
Unassigned, then deleting the "Band No More" category, making a new category
without the term "Band," Assigning one person to the new category, making a
new view, and checking the results. It worked. I am not sure what went
wrong.

From now on, when reassigning categories on contacts, I am going to be
careful about a/ using similar words in the category name and b/ reassiging
by right-clicking, not opening, and making the new view with one person and
checking it. Then I will feel confident that I can reassign several people
with correct results.