How do I record 2nd track by listening to 1st track? And most importantly prevent 1st track should NOT get recorded (or I call it bleeding) into the 2nd track.

I use a Allen+Heath ZEDi10 connection is as follows:

M3-M4 is connected to Roland JV2080 Mix L/R.
ST1 - is connected to Korg PA 900.
I tried various combinations of US OUT (Audio) to turn off - Main Mix getting fed back into the new track. I was unsuccessful.

Any ideas? As how I can record audio tracks by listening to existing tracks? How do I bypass USB feedback into the next track?