[CentOS] (c 5.6) Running 2 versions of Apache ?

Just wondering how to run 2 versions of Apache on the same server,
listening on different IPs and both on port 80. 

Does one give them, the httpd, different names and effectively duplicate
most of the Apache set-up ?

I use Apache;s virtual hosts facility for normal purposes but this is
for a different project. 

Thank you.

Paul.