I know these *old keyboards questions* are going on everybody's nerves, even on mine, and I am just lurking here, but I really need help now. Sorry.

When I use my MS50 trough midi sequencer on my pc, and when I'm recording, for some reason it records 3 (three!) notes for one note I play. And that is without the software's MIDI THRU option. If I check it, then I get those three notes PLUS three more one octave higher. Please, someone, do I need to edit some parameters on the keyboard itself, or just change the sequencer? I am using Jazz ++ Midi sequencer, because it is very simple - is it also dumb? Unfortunately, I dont have a manual of the keyboard, so I dont understand what some abbreviations do (among other stuff). :-(
I am aware that I probably created some kind of MIDI loop, however, I hope that only solution is not to plug out one of the cables, because I'd hate to have to plug it in/out all the time. Please help ...