This is because of the rule of priority.

Priority is the term we use to indicate who has the best right to register the trademark.

A Norwegian trademark application has priority from the date on which the application was received at the Norwegian Industrial Property Office. If you apply in other countries within six months, you can claim the same priority date as in the Norwegian application. Your application will then be protected from this date, and have priority over any similar trademark for which an application for registration is made at a later date.