I assume the .lock file refers to a specific catalog file at a specific location.
So if the catalog is stored locally as two separate instances, it should still open, and the .lock file doesn't apply.
I just tested this on my Windows 7 system with LR CC 2015.8 by copying the lock file to desktop, closing LR, and pasting the Lightroom CC Catalog.lrcat.lock file back to LR Catalog folder. LR relaunches with no issues and over-writes the original Lightroom CC Catalog.lrcat.lock with a newer date/time version. Just to be clear this is using one (1) system only.
Here's what the lock file shows in Notepad:
C:\Program Files\Adobe\Adobe Lightroom\lightroom.exe
The 4-digit number changes each time LR is relaunched, but there's nothing else in the lock file I can see. LR should NOT launch if a lock file is present. Perhaps there is some code that records successful program closure (no pending catalog database updates) and ignores the lock file?
Sorry for the late answer, but thanks for your testing.
Since this is the first time I post something on an Adobe forum, I have another question which you can hopefully answer:
although I created the screen name 'frabet', I see in this conversation our real account name. What name do you see ?
We only see the screen name "frabet". Your real name is only visible to yourself, when you are logged in.
Yeah, this has caused a lot of confusion for a lot of people, but don't worry