--no-remote (and --new-instance) prevents duplicate instances of same profile, not just different ones
It's understood that --no-remote (and --new-instance, though with slightly different abilities) will allow the -P {profile name} to function when a previous profile is already up and running.
That works as expected, thus this works (tested under Linux Mint/zsh)
---> firefox --no-remote -P Dwight {............} and ---> firefox --no-remote -P Schmidlapp {............} (with both running).
HOWEVER,
When profile Dwight is running, and I try to execute another run at the same time of a Dwight profile, I'll get the same old error message (attached) on the second run.