Question related to FreeBSD Serial Console...

I have a question related to FreeBSD Serial console,

I am aware you can use -Dh for both internal and serial, but is it
possible to see the 'kernel' "boot" messages sent on both the serial and
the console?

It was a question that was asked to me by a client, and after
researching it more, it seems that it's not possible.

Am i wrong?  or did I miss an option that's not documented?

Sincerely,

Scott M. Likens