Necdetdoni it is not problem and the solution is it:

If we play mp3 and we use Start button or (5/10) key, for example if we play a mp3 from player 1, and we select a mp3 from player 2, the player 1 end to play...

If now start the mp3 from ENTER button then play parallel player 1, and player 2....

Please try it...
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Style Producer
Ketron Event, Ketron Audya 76, Audya 5, SD9, SD1,Yamaha Genos, Korg Pa3x, microarranger, Roland Fantom G6, V-Synth XT, XV-5080, SH201, D-50, Novation KS4, Dave Smith Evolver