We present a case study of the solar flare ( SOL2001-10-02T17:31 ) that showed quasi-periodic pulsations ( QPPs ) in hard X-rays with two simultaneously excited periods , P _ { 1 } = 26 - 31 s and P _ { 2 } = 110 s. Complete evolution of the flare recorded by the Yohkoh telescopes , together with the patrol SOHO /EIT images , allowed us to identify magnetic structures responsible for particular periods and to propose an overall scenario which is consistent with the available observations .
Namely , we suggest that emerging magnetic flux initiated the reconnection with legs of a large arcade of coronal loops that had been present in an active region for several days .
The reconnection excited MHD oscillations in both magnetic structures simultaneously : period P _ { 1 } was generated in the emerging loop and in a loop being a result of the reconnection ; period P _ { 2 } occurred in the arcade .
Both resonators produced photons of different spectra .
We anticipate that multiperiodicity in hard X-rays can be a common feature of flare hybrids , i.e . the events , in which magnetic structures of different sizes interact .