two flavours on one computer
 

Hi,

Can I install two flavours of linux on one system i.e redhat and suse one one system , which has single processor?

You can install as many as you like. You are limited only by hard drive space.

Linux is extremely flexible in this regard. It can boot from anywhere, even logical partitions.

If you want to run them parallel you need virtualization techniques like xen or vmware and the like.

I have done windows/linux dual boots but never dual linux systems.

IF i wanted to install Debian and UBuntu which should I install first ?

It doesn't matter. You can install them in any order.

Just make sure after you installed all of them that you add them to your bootloader menu. If you're using grub that's menu.lst .