with t as 
(select *
   FROM oleg MATCH_RECOGNIZE 
   ( ORDER BY dt1, id
     MEASURES
        STRT.id AS mrid,
        STRT.dt1 AS mrdt1,
        nvl(NN.dt1, STRT.dt1)  as mrdt12
     ONE ROW PER MATCH
     AFTER MATCH SKIP PAST LAST ROW  
     PATTERN (STRT NN+ | STRT)
     DEFINE
         NN as NN.id = PREV(NN.id)
   ))
select mrid as id, mrdt1 as dt1,  max(oleg.dt2) as dt2 from t, oleg
where oleg.id=t.mrid and oleg.dt1 between t.mrdt1 and t.mrdt12
group by mrid, mrdt1 
order by 2, 1