yes.

The disk types of IDE or Sata do not matter, neither the sizes between 2.5" and 3.5".

However to boot properly without any more work you must use the disk in the same boot disk order as before. This is to say if it been booted up as a sdb before then it should boot same as sdb in the new environment. To alter the disk order in Linux is possible but requiring correction to the boot loader configuration files and fstab. Also certain server type Linux distros, like Red Hat, dislike being moved and have Selinux preventing such a migration. The movement can only be achieve by disabling Selinux at least initially.

If you use an old kernel that sticks to hda to hdd device names and move it to a Sata you need to amend the boot loader configuration and fstab too.

The other golden rule is to use the target disk either exactly in size or just larger than the source disk.

Thank you very much for your help. So I need to obtain another ide-to-usb adapter and then clone one of the primary working ide disks to another formatted one through 'dd if of' utility. Can you please let me know how can I make my centos dual boot with redhat?

You don't need any formatting operation if you clone the whole disk?

I can't see why CentOS and Re Hat cannot be dual booted, as these are just 2 of the 30+ Linux in my hard disk. Just remember to use the clone in the same condition as the source disk otherwise you will have to do extra work.

So , according to you, the second ide disk does not need to be formatted first (it just needs to be of the same geometry as the first one). Can you please let me have a reference link on how to dual boot my centos with redhat?

When you clone a first hard disk onto a second hard disk you force the second hard disk to become a mirror image of the first. Both disks have identical partition table and inside the area prescribed by this partition table every binary bit is the same in the two disk. Formatting the second disk is just a waste of time regardless you can get it right or not. The second disk by default will have the same geometry of the former.

Both CentrOS and Red Hat use a Linux boot loader which can be Lilo or Grub. Grub is the preferred choice in all the versions I have come across these two distros.

Any Grub, be it a Grub1 or Grub2, can boot any Linux directly. Additionally a decent boot loader like Grub can indrectly boot any other PC boot loader from Windows, BSD and Solaris.

Therefore there is no installed PC operating system Grub cannot boot!!!!!!!!!!!!!

If you must see a link to convince yourself this thread has one Grub booting 145 operating system using indirfect method because it is easier. Red Hat and CentSO were the 2 among the 145 system. They were installed in hda11 and hdc11 respectively.