You can open dual browser windows for reference back and forth. For instance, you might want to keep the Find Agents/Offices window open so you can look up multiple agent IDs, while you work in another part of the software.
To open a second browser window -- While you're in the MLS, right-click on a link or menu item and choose "Open in New Window." This opens the page in a separate window, without closing the browser or page you were in.