Counting specific values of a field and creating an incremental ID
I have a table with the following fields, FieldA and FieldB. I have a field named PrelimName which is a calculated field as "FieldA & " " & FieldB". So let's say a record has an ABC typed in FieldA and XYZ typed in FieldB, my PrelimName field would automatically be calculated as "ABC XYZ". I do not want my PrelimName field to be unique as I may have multiple instances of a record with these characteristics. However, I do ultimately want a unique ID which would incrementally count each time a new combination of "ABC XYZ" appears; in Field FinalName which would auto calculate an incremental count of the prior times "ABC XYZ" appears. For example, when a second record that has this "ABC XYZ" combo is entered, field FinalName would auto calculate "ABC XYZ.2", and a third record with the PrelimName "ABC XYZ" would show a FinalName of "ABC XYZ.3". And so forth. How can I get the number of times "ABC XYZ" appears in the table under PrelimName so I can append that value as the incremental count for FinalName?