You can easily run Multiple MC Servers. You simply need to change the external ports, Be sure to use an unused port. There is no need to change the Minecraft port or RCON port in the server.properties
To easily get Plugins in to your MC server since PVC's are in use for the config storage you can add a host path storage for either /mods or /plugins depending on what your server needs like so
This will give you an easy folder to drop the plugins in and they will then sync to /data/plugins or /data/mods , you will/may need to shell in to the app to periodically clean up old versions
For the second server instance the setup is about the same one minor difference is the need to change the port for dynmap in the container to a new port and configure like so (note this could of just been my system being silly due to my tests and not rebooting)