First type '''about:preferences#sync''' on your laptop's Firefox browser. This will open Sync settings. If it shows your email address, click on the '''Disconnect''' button and you'll see two options. Click "'Create Account'" and create another account. And this is how you can sign in with two different sync profile. But I will highly recommend you not to use above method, instead create two different Firefox local profile. You can see all information about profile here: [[Use the Profile Manager to create and remove Firefox profiles]]