Hi, I had a similar problem, the BPM from my DAW and the BPM from the 9500 would display the same value but would be slightly different by .2 or .3 BPM which is enough to be unpleasant to listen. My aim was to record loops in the 9500 coming from the DAW to make it fit perfectly but the end of the loop was always messy due to the slight difference. I managed to do it by adjusting the BPM within my DAW to make it fit the BPM of the 9500 (just like a vinyl DJ would do to adjust the BPM by ear).
Set your first looper on XT mode by pressing ”EXT clock” once. Plug a MIDI cable in the MIDI IN port. This will be the slave.
Plug the other end of the cable in MIDI OUT on your other looper. Do not press ”Ext clock” this thime. This other looper will be the master.
Now you should be able to control both loopers tempo from the master looper