There's no reason this should be denied:
set system static-host-mapping host-name test1 inet 10.0.10.100 set system static-host-mapping host-name test2 inet 10.0.10.100
static-host-mapping "test2" address "10.0.10.100"already used in another static-host-mapping [[system static-host-mapping]] failed
There's an extra error check in host_name.py causing this.