If change happens on any tab URL, the extension will check if the domain of new URL is matching with the defined and configured domain URL pattern.In case if there is a match all the tabs will be checked for configured domain URL, and if any tab found with the same domain the new URL will be opened in the already existing tab and the tab sourcing the URL will be closed. You can configure the domain URL from the extension options link on the extension details page. The extension is also sending notification if a match happen what can be switched off on the options screen.