Excel Conditional Formatting - Highlight Second Instance Of Combination

I need a conditional formatting formula that will highlight the second instance of a combination of values from two columns.

For example, Column A is a person's name and Column B is a drop down with 3 options (Street Address, Phone Number, and Email Address). If Row 2 says John Smith (Column A) and Street Address (Column B) and Row 6 also says John Smith (Column A) and Street Address (Column B), what conditional formatting formula would I use to highlight Row 6 as duplicate information?

Name
Information

John Smith
Street Address

Mary Black
Email Address

[Code] ..........