Conditional format the cell that's different

Background: I have a large worksheet with 87 columns and ~13K rows. Every column has lookups to a source workbook.

The Problem: The source workbook will change the number of rows it contains. I want to ensure that my workbook picks up every row from the source workbook, so have a formula above every column to show the row number of the last filled cell in that column. So, I have 86 values of "13132" and one value of "13130". When I'm looking at my worksheet as a whole, how can I get the different one to pop out so I'll catch it? I thought of CF but can't figure the formula to use. I tried "=A2<>B2" but it colors my last column because the value next to it is, of course, zero. Also, it highlights the "right" number to the left as well as the "wrong" number to the right.

I've attached a brief example. Any help would be appreciated.

This maybe?

=COUNTIF($A2:$BJ2,A2)=1

Don't know whether to be ashamed I didn't think of it, or properly grateful that God put wonderful people in the world who think differently than me. Thanks AliGW; that was EXACTLY what I needed!

Sometimes, you just need a jolt to remind you how simple things can be. Been there myself many times - wood and trees spring to mind.