data new; 
input system $ findings $ visit $; 
cards; 
car abnormal base 
car abnormal base 
car normal base 
car normal eot 
car normal eot 
resp abnormal base 
resp abnormal base 
resp abnormal base 
resp abnormal eot 
resp normal eot 
resp normal eot 
; 
run; 

PROC SORT VERSION:

proc sort nodupkey data=new out=res_nodup;
   by system   findings;
   run;

PROC SQL VERSION:

  proc sql;
   create table res_nodup_sql as
   select system,
   findings,
   visit,
   monotonic() As row_numb ,
   min(calculated row_numb) as indicator
   from new
   group by 1,2
   having row_numb=indicator ;
   quit;