How to find Records in Two Tables that Have the same values in one column but different values in another column?

[Mr. Snrub]

I have two Excel tables formatted as tables, Table1 and Table2. They both have a field "Case Number." Some case numbers are the same in both tables, and some are different. I also have a field in Table1 called Table1Office and a field in Table2 called Table2Office. I want to create another table Table3 that will only show case numbers that appear in both tables, but have different values for Table1Office and Table2Office. What is the best way to do this? Should I just try and merge both tables (giving me a whole lot of empty space, since I don't really expect there to be all that many instances where Table1Office != Table2Office), or is there a better approach?