another try

proc sort data=dataset; by name date; run;

data dataset;
set dataset;
by name date;
if first.name then do;
counter=0;
retain counter;
end;
counter+1;
run;

proc sql;
select name, avg(ret) as avg_ret_1 from dateset
group by name;
run;

proc sql;
select name, avg(ret) as avg_ret_2 from dateset
where counter gt 1
group by name;
quit;