https://oxidemod.org/threads/lgsm-multiple-rust-servers-modded-vanilla.16475/
I haven't done this myself but this way you don't need to have duplicate rust containers. I would recommend using ports that are in steams range for rust so incase there are people with hardened firewall rules out there they will still be able to connect. Maybe it's been made easier since then I'd check the config file for notes about changing the rust servers pid in the config file. YMMV