Following your instructions from this example, I was able to launch the two vMX instances in two separate containers.
The following screenshot shows the output when I executed the command show interface and the command show route from one of these vMX instance:

From the CLI of one vMX instance , I was able to ping the IP address of the fxp0.0 interface of the other vMX instance, and vice versa. However, the IP address of the ge-0/0/0 interface is still NOT REACHABLE via ping. Do you know the root cause of this problem and how to fix it?
Also, considering this vMX command: set interface ge-0/0/0.0 family inet address 10.10.10.2/24
Do you know if the interface ge-0/0/0.0 for an vMX instance is supposed to map to a physical NIC (such as eth1) of the Docker Host machine where the vMX container is running (similar to the sample vMX startup configuration shown on page 34 of this link: https://www.juniper.net/techpubs/en_US/vmx15.1/information-products/pathway-pages/getting-started/getting-started.pdf)?