Data Class;

 Set Sashelp.class;

 Output;
 If _N_= 5 Then Output;

Run;

Proc Sql;

  Select
         name into :AllVar separated by ','
  From
         sashelp.vcolumn
  Where
         libname= %Upcase('WORK') and
         memname= %Upcase('CLASS')
  ;

  Select
         *
  From
         Work.Class
  Group
         By &AllVar
  Having
         Count(*) > 1
;
quit;
run;