Can there only be pairs or singles? and is data sorted or unsorted?

"DC" wrote:

Does anyone have any suggestions on how to solve the following.

P MCC
A 589 1520
B 589 1520
A 542 1711
B 542 1711

I want to automate the addition of letters A & B to the spreadsheet where a
pair exists between fields P & MCC, like in the above example.

Can this be done?