/dev/cdrom is a symbolic link to something along the lines of /dev/hdb or /dev/hdc etc... One way to pin point what your other drive is, as root, pipe the output of dmesg to more or less and just filter through the contents till you find it.
Once that is done, and you have found it, and are sure it is your other cdrom drive, you can create another symbolic link in /dev for the future.
ln -s /dev/name_of_cdrom /dev/cdrom2
This will now make a sym link (short cut) named /dev/cdrom2 which now links to your 2nd cdrom drive.
All you need to do now is edit your /etc/fstab and add the /dev/cdrom2 entry in. Just copy the /dev/cdrom one that is in there now and change the values.