Conditional formatting formula to format cells not equal to a group value

[Marcia]

Hello. Is there a conditional formula that will highlight a cell having a value that is not equal to the group. Like in the image, B4 and B10 should be formatted as different. The criteria is, the first name listed beside a number should be the name for all similar numbers. The first name in number 1 is AA so all names for 1 should be AA. Thank you.