Two realms vs two containers

[JacopoDEV-ITA]

Hello,
I've a production server (Ubuntu) with Docker and a running Keycloak container. Users of this realm are shared between two platform, one is mine and the other is managed by a partner company.
Now I need to create a new tenant of my platform and I would like to re-use as much of this architecture as I can. I would easily go for a new realm in the existing Keycloak environment BUT I also would like to keep things separate and not having the guys from the other company to interfere with this realm (they also have root access to the Ubuntu VM).
Is there any way I can achieve this? Cloning the container would help?
Do I need to pay for a brand new vm?
Any suggestion is really appreciated