This effort will complement test review for launch bug issue 789746
All display_* chameleon tests have the ability to iterate through all ports found on chameleon that areconnected via the loop
for chameleon_port in finder.iterate_all_ports()
E.g. https://cs.corp.google.com/chromeos_public/src/third_party/autotest/files/server/site_tests/display_SwitchMode/display_SwitchMode.py?l=68

We had a single device in the past set with two display connections to chameleon, but was never looked at as it was left in nightly build..., and now it is no more in this setup. So currently a single display only is tested.

For this we might need:
1) test bed change - additional cable(DP-to-DP or typeC-to-DP) connecting the second display port(either DP or TypeC) to one of the chameleon DP ports.

2) Test code change - we want to have a specific test that does examine both displays after switching to mirror mode and confirming test calibration image check is OK. The current tests set the EDID and switch to mirror mode after the port is selected, and we want the opposite. We have to find out if it is doable.

3) The current test suite and device labels set all tests in the suite to be executed. That means if we do not want to mix single with dual display tests, we might be better to write a new test or several tests, and run them as a separate suite. 

4) We should still find out is there a value of testing dual display with the current way tests are written

Tom, can you help us find out about applicability of new vs old tests?