Hello,
How are you connecting your guitar/instrument to the H90? Are you using a mono input/output, stereo input/output, or something else?
When you are using an algorithm with an A and B voice, then the A voice will be panned to the left output, and the B voice will be panned to the right output.
You also need to make sure the Pitch Mix or Delay Mix parameter is at a value where you will hear both voices.
A simple example to test would be to load the Digital Delay algorithm and the default preset will have 2 delays at a 1/4 rhythm. Change one of the delay times you should hear both voices.
