How can I reuse my LUKS password at boot?

[Todd And Margo Chester]

Hi All,

I now have two encrypted hard drives.  The second one is my
backup drive.  Both have the same password.

When I boot up, I get prompted twice for each drive.  My
password is rather long and it is a bit annoying to have to
put it in twice, let alone once.

Is there a way get LUKS to automatically reuse my password
from the first drive on the second drive at boot?

Many thanks,
-T