1  with t as (
  2  select 42 id,date '1999-03-03' d from dual union all
  3  select 42 id,date '1999-03-03' d from dual union all
  4  select 50 id,date '2002-02-02' d from dual union all
  5  select 50 id,date '2002-02-02' d from dual union all
  6  select 50 id,date '2002-04-04' d from dual union all
  7  select 34 id,date '2003-03-03' d from dual union all
  8  select 34 id,date '1999-03-03' d from dual
  9  )
 10  select id,count(distinct d) cc
 11  from t
 12  group by id
 13* having count(distinct d)>1
SQL> /

        ID         CC
---------- ----------
        34          2
        50          2