CONCATENATE Question

[nwpassage]

I'm concatenating two cells. One is a Parent organization name and the other is a location name. I want to concatenate the two. That much I've got. Sometimes the Parent and location names are the same. Is there a way to say:

Concatenate the two cells UNLESS the two are the same?

Thanks.

[Speshul]

The red will happen if they are the same, change if you need to
=if(a1=b1,a1,concatenate(a1,b1))