This might have been reported already but I'm not sure.
When I append &unlocked=no to a URL that's gotten by doing a faceted search for works by a particular publisher that are in Pre-Pub, it does not weed out any of the books I already own.
https://www.logos.com/products/search?Publisher=Eerdmans&Status=Pre-Pub&unlocked=no
EDIT: Found the other thread. People there said it was fixed, but it apparently isn't.
EDIT: That thread was not the same problem. Disregard.