[Lynne]

No, you may no. You may install a test forum that is not visible to the public for testing purposes only. See your License Agreement:

• vBulletin license grants you the right to run one instance (a single installation) of the Software on one web server and one web site for each license purchased. Each license may power one instance of the Software on one domain. For each installed instance of the Software, a separate license is required. Modifications to the Software or database to circumvent the one-license-one-board rule are prohibited.
• If you have a valid Software license, you may set up an additional test forum in order to test code, template and database modifications. To make this clear to us and our license verification procedures, place it in a directory called 'testvb' and be sure to password protect it. It must not be accessible by the general public.