I am trying to figure out a formula. I need to know how many times a certain issue happens based on case numbers. Meaning there are multiple entries under a specific case number for that subject, but I only want to count it once. I used the formula below and I can get the total number of entries for that subject; but that is not what I am looking for. This is counting every instance of the word "Custom" showing up.

=COUNTIF(Source!$G:$G,"*Custom*")

In column Source!N I have case numbers which would be the filter that should only count once. This number will appear everytime someone comments in that case and I do not want it counted multiple times.

Any ideas on how to do this?