As a root create two users and execute tmt run for each of them in sequence:
# useradd A
# su -l A
$ tmt init -t mini
$ tmt run -a provision -h local
....
total: 1 test passed
$ logout
# useradd B
# su -l B
$ tmt init -t mini
$ tmt run -a provision -h local
...
warn: Test failed to manage its pidfile.
...
total: 1 error
As a root create two users and execute tmt run for each of them in sequence:
Debug output shows