How would I run two Apache web servers on the same box

How would you go about creating two Apache v2.x servers on the same machine - listening on two different ports?

Intially - would you require a new directory tree? Can you construct within the same? Beyond that - what are the configuration requirements?

This is specific for Apache. Any insights would be appreciated - thanks.
[ February 27, 2008: Message edited by: bob reilly ]

Is there any reason to have them in the same directory? (Don't know if it would work).
Else, taking two directories, you just have to change the port of one instance, fire them both up and you should be done.

Why have two instances, when a single instance can be configured to listen on two different ports, with different hosts, web roots and everything?

Originally posted by David O'Meara:
Why have two instances, when a single instance can be configured to listen on two different ports, with different hosts, web roots and everything?

I agree with David. Installing two differnet server instances just for listening to two different ports doesn't make sense at all.

If, it is in any case unavoidable, then please specify your requirement.

You've pretty much confirmed my expectations. There is as far as I know no need. My attempt would be to create one instance - listening on two different ports.

Thanks guys.