Highlight duplicate cells in next column...

Column A has a list of Entity ID for each customer.
Column B has a list of Entity ID's in multiple instance for how many service appointments they have.

So in Office 2007, I can go to - conditional formatting -highlight cells - equal to. BUT, in only lets me select once cell in Column A to match in Column B.

I need it to look for all the numbers listed in Column A, and Highlight all the matching numbers in column B.

Ive thought about putting the ID's all in one column, and use conditional formatting to find unique, but since some people have two service calls, they dont come back as unique, even though that customer is unique since they dont match my list.

Attached is a sample sheet. The list will be very large so I cant go one by one.

Thanks for the help!