Not exactly. According to search they doesn't. Not as two kernels (or more?) in a one system. But for now they do exists as a virtualization - any systems on one machine/cluster. I'm curious whether anyone would be interested in an Unix with two kernels. One Linux kernel as a privacy and one could be BSD as a proprietary to do business things. This could run on RISC. Anyone would be interested?

On Ubuntu /etc/libvirt/qemu/redhat-amd64.xml

virt-install --virt-type kvm --name redhat-amd64 \ --cdrom ~/Downloads/RedHat.iso \ --os-variant redhat9 \ --disk size=30 --memory 3024