2nd linux install overwrites MBR of 1st linux install

I have two hard disks, hda = 120gb and hdb = 40gb. I want to install two LINUX operating systems. I would like to have the option of booting into the operating system of my choice at boot time. I am currently running Fedora Core release 3 (Heidelberg)
Linux 2.6.9-1.681_FC3 on hda. When I try to install the 2nd system on hdb the boot loader overwrites the MBR on hda. I am lost as to how to get around this. I am not currently nor do I plan to run Windows. I am reading info pages on Grub and Parted, but I feel a little overwhelmed and could use a little guidence. I would appreciate any help to get me pointed in the right direction. Thanks,
stanch

What version are you installing as the second Linux?

All Linux installs ask you where to install the bootloader. You may have to choose some advanced install method if it doesn't for you.

Just tell it not to install a bootloader at all or don't put in the hda MBR. It usually gives you a choice between the MBR and the Linux parition IIRC. Just put the second instance onto the new Linux partition.

After that edit the original bootloader's configuration so you can boot the second Linux instance.

You could also use a common boot partition for both of your Linux installs but that would take some more tinkering.

Actually, I want to install the exact same operating system, FC3. I would like to keep all my important files and email contacts on the first system. The second system would be basically bare bones and used for self training, experimenting, and just trying new things. The 2nd one I would be willing to lose and re-install if I really messed up. Later if desired I could test out other distros and/or new releases. Does this make any sense?
Anyway, thanks for your help. It might take me a day or two depending on what happens.
Thanks very much for your help. I'll let you know how it turns out.
stanch

What version are you installing as the second Linux?

All Linux installs ask you where to install the bootloader. You may have to choose some advanced install method if it doesn't for you.

Just tell it not to install a bootloader at all or don't put in the hda MBR. It usually gives you a choice between the MBR and the Linux parition IIRC. Just put the second instance onto the new Linux partition.

After that edit the original bootloader's configuration so you can boot the second Linux instance.

You could also use a common boot partition for both of your Linux installs but that would take some more tinkering.

Thank you for your help. I re-installed FC3 on the 2nd hard disk and wrote everything down as I went. The choice for (boot) in FC3 is MBR, 1st Partition on the hard disk, and no boot install. I took the 1st partition. Then it was basically changing drive numbers,and VolGroup numbers. The first update is to a new kernel, so I had to do it all over again. But, I am up and running with two linux systems with all updates completed! Thanks a bunch for your help. Is there somewhere on this board I can update to give you credit for all your help? I do appreciate it. Thanks again.
stanch

You just gave me all the credit I would ever want or need.

Good to hear it works now and feel free to ask again if you have any problems :)