Yep. I have destroyed the freshly installed stretch container and now my other one (Sid) doesn't start. I only get the 'No Xwayland window' screen rather than the desktop. I guess, shouldn't have tried to install more than one container at the same time.
# Container specific configuration lxc.rootfs.path = dir:/home/.lxc/<container_name> lxc.uts.name = <container_name>