Yes, you can do this with PROC FREQ and send your output to a data set
rather than the ODS. You don't even have to concatenate the variables.
Just sort by 1 and then the other. Have a look at the following:
input var1 $ var2;
PROC SORT data=temp; by var1 var2; run;
proc freq data=temp noprint;
tables var1*var2 / out=check (drop=percent where=(count ne 1));
Does this help ?
Central Statistics Office