Excel nested IF question for checking duplicates name in earlier columns

I would like to seek help on setting up a nested IF for my excel formulas.

This is the way my data is being entered by another colleague. For example, on a daily basis, he records the type of fruit being delivered, and to which stall it was delivered (columns L to V).

This results in stall being mentioned twice or multiple times in each data row, which doesn't allow me to use my COUNTIF function as there are repeats.

However, I just need a formula to show me which stalls were delivered fruits (minus the stall name being mentioned twice as they received two different types of fruits). I wanted to set up 5 columns at the end of my table to do some nested IF functions. Basically, columns X to AA would have formulas to identify if the store name in M,O,Q,S,U would be repeated.

Column Y = column O (if not identical to column M), if column O and Y were identical, reference column Q (if column Q is not equal to column O and Y), otherwise reference column S.

Basically, I should not have store names repeating in row display between column X to AB.