you can achieve this by using virtual hosts.
the first step is enable bindaddress in httpd.conf file, so that is listen to ip address or url
BindAddress *
the second step is to place an ip address in the NameVirtualHost that is
NameVirtualHost xx.xx.xx.xx
virtualHost xx.xx.xx.xx
ServerName
www.mydomain.com
virtualHost xx.xx.xx.xx
ServerName
www.myseconddomain.com
Note:
xx should be an ip address.
you will only be able to access the web site only through an iP address without configuring DNS