Run multiple Unity players in parallel in Linux

Hi, I have a Unity player that is designed to run for a few minutes, saving screenshots, and then exit. I'd like to run multiple instances of the player in parallel on my workstation, but it seems that even if I launch multiple instances of the player process, only one will actually execute at once. The others idle until the active one exists. Does Unity use some kind of locking mechanism on Linux to only allow one player to run at a time? If so, is there a way to get around it? Thanks!