I got both on reboot ok now. Turn out, I should not disconnect the 1st hdd when installing CentOS on 2nd hdd. I reconnected 1st hdd and re-install CentOS on 2nd hdd and voila the reboot recognized the 1st hdd. Thank you for your replying.
I would have left it as is and used the bios to select the boot disk. Now, if you ever decide to remove one of the OS's you will have to figure out a way to fix the boot loader. if you left it as it was, then you don't have to mess with the boot loader when removing an OS.