You can PLAY two notes at the same time in QB64May 11 2011 at 1:35 PM
Response to Playing multiple frequencies at one time with SOUND
With PLAY "A, B, C" it can play 3 tones, but you have to figure out the frequencies.
You can also use _SNDRAW left, right to do two frequencies in two speakers.
Newbies usually go to www.qbasic.com and click on
The QBasic Forum
Forum regulars have their own ways, which include
The QBasic Community Forums