Cross-checking list to determine overlap of entries

Hello,

I have a list of usernames and the website to which they have access. I need to be able to determine if a customer’s username is unique or if they have the same username for other websites. Some of the usernames are also duplicated for the same website. I've attached a sample file.

Any help would be greatly appreciated in how I can complete a cross check using a formula.

Thank you

SampleFile.xlsx

This is perfect. Thanks so much Lem