Ah, yes, Workstation 16 raised the default value from 1GB to 8GB. I lowered it to 1GB now, so both VMs use 1GB.

Still, it doesn't work. 2 * (12 + 1)GB ... are there still some hidden requirements?

BTW: The label for this option reads: "Maximum amount of guest memory that can be used for graphics memory:" So, I tend to believe the value entered here is taken from the guest memory amount, not added...?