This happens only if users log in the site with both browsers. The plugin keeps the information of unlogged users in a cookie, while it stores information of logged in users in the database. As cookies are stores in the browser, users have to log to the site to recover their recently viewed products. This feature is available only in the premium version of the plugin.
Products will show in the detail page of any product, and everywhere you want using its widget and shortcode. Once installed, the plugin will install the “Recently Viewed Products” page, which you can use to display easily all recently viewed product of the user. This feature is available only in the premium version of the plugin.