Purpose of syslog and messages are two different. I don't think its good to mix those. /var/log/messages is the usual place to all system software messages, non-kernel boot issues, and messages that go to 'dmesg'. Purpose of the syslog is to be the audit log and it will log everything and that's why you would fine every thing in /var/log/messages in the syslog. If you consider that as duplication of messages, I don't think that's correct.
Purpose of syslog and messages are two different. I don't think its good to mix those. /var/log/messages is the usual place to all system software messages, non-kernel boot issues, and messages that go to 'dmesg'. Purpose of the syslog is to be the audit log and it will log everything and that's why you would fine every thing in /var/log/messages in the syslog. If you consider that as duplication of messages, I don't think that's correct.