Detect if entries have duplicate criteria

Hi

I have two tables. The rows in the first table have a 1-to-many relationship with items in the second table.

I want a formula that I can copy down under column Ok-to-treat-like-app that will result in Y or N if, for all entries in second table, the values for VendorSupport & SupportedBy are the SAME for the same AppGroup. I want to be able to add to both tables as times goes on without modifying the formulas

In the case of BIEM above, it would be Y
In the case of Maximo above, it would be N

Can anybody assist? I checked the posts for something similar, but I haven't got it yet.