ZSK pre-publish

[CT]

I have a few static zones that I sign via script
keydir = directory for both KSK and ZSK
$zone = zone file
/usr/local/sbin/dnssec-signzone -S -g -a -H 10 -3 $SALT -K keydir $zone


Fetching KSK 4054/RSASHA256 from key repository.
Fetching ZSK 36948/RSASHA256 from key repository.
Fetching ZSK 65304/RSASHA256 from key repository.
Verifying the zone using the following algorithms: RSASHA256.
Zone signing complete:
Algorithm: RSASHA256: KSKs: 1 active, 0 stand-by, 0 revoked
                                        ZSKs: 2 active, 0 stand-by, 0 
revoked


My question is that both zsk's are published, how do I make 1 standby

Thx
CT