This can be done yes, if you have root access you can sort this out, assuming you've set up your /home/user/www or /var/www/ folder you can create 2 different folders for each domain under the specified folder (We will use /var/www for example) so /var/www/domain1 and /var/www/domain2. Under your Apache configuration (if you use Apache) add a vhost (Google "setting up an apache vhost" this will get this done for you easily). Set them up for /var/www/domain1 to link to www.domain1.com and the same for the other if you get the drift.
If your server is capable to run both forums then yes, lease the other and save some money doing this. Good luck