An apparent bug in VyOS 1.3:
set system static-host-mapping host-name myhost inet 10.0.0.1
set system static-host-mapping host-name myhost inet 2001:db8:abcd::1
What should show:
I think if you just added an inet6 parameter to the host-name leaf then that would work.
Currently the 'inet' parameters accepts both IPv4 and IPv6 addresses.
With the change to have both 'inet' and 'inet6' then 'inet' would be ONLY for IPv4 and the inet6 would be ONLY for IPv6 addresses.