Is possible to have wamp and a separate apache server on a machine? Will it work?

The short answer is yes. You just need to point the other to a different port (since both will try to use the default port, which is 80). In your httpd.conf file, find the line that says Listen 80 and change it to some other value (e.g. Listen 81)

Personally, I make use of (Named) Virtual Hosts. In your WAMP, you may configure your httpd.conf or extras/httpd-vhosts.conf to add multiple VirtualHosts.

Here's a sample configuration that you can add to those configuration files:

<VirtualHost *:80>
  ServerName yourproject.local
  DocumentRoot /path/to/your/project/

  <Directory /path/to/your/project/>
    DirectoryIndex index.php
    AllowOverride All
    Order allow,deny
    Allow from all
  </Directory>
<VirtualHost>

Then I append the following in my hosts file /etc/hosts in Linux and C:/WINDOWS/system32/drivers/etc/hosts in Windows XP:

127.0.0.1 yourproject.local

Notice the the value of the ServerName directive in the configuration file is the same as the one that I appended in the hosts file.