Z, this is already how the rule about talent doubling works. The only way you get a doubled talent is if you get it from both your race (blood talents not allowed) and from your profession, and the profession doesn't allow any other options to be taken in place of that talent.
In fact, the only race/profession combination I can think of that even has the option of a doubled talent is a gnome who starts off as a mage class (whether the one from the core rules, or College of Magic's elementalist, necromancer, thaumaturge, or vivimancer). In that case, you can double down on the Sense Magic talent.