来个VBA解吧
Sub test()
Dim rng As Range
For Each rng In Range("a2", [a65536].End(xlUp))
If Application.CountIf(Range("A:A"), rng.Value) = 2 And Application.CountIfs(Range("A:A"), rng.Value, _
Range("B:B"), rng.Offset(0, 1).Value) = 1 Then rng.Resize(1, 2).Font.ColorIndex = 3
Next
End Sub