Frontpage:

Switch to Folders view, click once on the product-description.htm page or the page you want to duplicate, press CTRL-C or right click on it and choose copy.  Then press CTRL-V or right click and choose paste.  Now you need to click on the new page once to select it, and then again to edit the name.  Rename it, making sure to keep the .htm extension.  Drag this page to the navigation view and your done!

Other:

To duplicate the file in Windows, simply click on it once, then press CTRL-C to copy it and CTRL-V to paste it.  Repeat for as many pages as you need.