select distinct (case when t1.id<t2.id then t2.id else t1.id end) id from t t1,t t2 where t1.id<>t2.id and dbms_lob.compare(t1.value,t2.value)=0;
select distinct t1.id from t t1,t t2 where t1.id>t2.id and ...
select t1.rowid from t t1,t t2 where t1.rowid>t2.rowid and ...