Excel: Keeping duplicates in data validation list in Excel

Excel: Keeping duplicates in data validation list in Excel

I am working on a tracker for a game in Excel. One of the functions I am
using is a drop-down list with a series of numbers, some repeated, for
character stats. I found some help to remove objects from a drop-down
after they've already been chosen; in this instance, I only need one of
them removed if there are multiples. Here's what I'm working with:
Column A has numbers 4, 3, 3, 2, 2, 2, 1, 1, 1, 1 which are the master
list contents.
Column B has a formula to generate a number to tell whether or not that
number has been used in that range. That formula is
=IF(COUNTIF('Character Tracker v1.0'!$B$25:$B$50,A12)>=1,"",ROW())
Column C has a formula to remove used entries from the list. Column C
itself is the list source. That formula is:
=IF(ROW(A7)-ROW(A$7)+1>COUNT(B$7:B$16),"",
INDEX(A:A,SMALL(B$7:B$16,1+ROW(A7)-ROW(A$7))))
For example: if I choose a 3 from the drop down, both instances of 3
disappear, and I only need one instance of 3 to be removed when chosen
(and if I choose another 3, that one disappears). I'm pretty sure it's the
formula in column B that I need to alter (as it generates a number which
is read by Column C to determine whether that entry is used or not), but
I'm not sure what to change.
Any hel pwould be appreciated.