Q. I am a faculty member teaching multiple sections of the same course. Can I use one single Moodle site for both classes?

Yes!  You can add students from your first section to your second section's Moodle site and only maintain one site.  Students should be added with the role of "unregistered".  Remember that this is a manual process, so if students add or drop the course from your first section you will need to remove or add users to the site accordingly. Here are the instructions for combining sections into one site in the Moodle Documentation.