The current hieradata for Solaris 11 uses the ssh::server::custom parameter to set ChallengeResponseAuthentication to yes. Attempting to override it by setting ssh::server::challenge_response_authentication to "no" causes two ChallengeResponseAuthentication configuration lines to appear in /etc/ssh/sshd_config.
Recommend controlling this setting to use using the ssh::server::challenge_response_authentication parameter within data/os/Solaris/11.yaml, so that it can be overridden elsewhere in users' hiera data.