zoneadm manpage lists '-m copy' as general option for clone
Snippet from the zoneadm manpage
clone [-m copy] [-s zfs_snapshot] source_zone Install a zone by copying an existing installed zone. This subcommand is an alternative way to install the zone. -m copy Force the clone to be a copy, even if a "ZFS clone" is possible. -s zfs_snapshot Specify the name of a ZFS snapshot to use as the source of the clone. The snapshot must be a snapshot of the source zone taken from a previous "zoneadm clone" installation. The source zone must be halted before this subcommand can be used.
It looks like the '-m' option is not a generic option but brand specific, the manpage should probably be updated for this.
I was trying to use it but both the lx and ipkg brand on OmniOS do not support this flag.