Multiple power meters - Tacx Neo 2T and 4iiii precision

Just got my Tacx Neo 2T trainer and paired it with my Fenix 5 without any issues. Beforehand I removed the battery from my 4iii precision crank meter to avoid "double power", but what happens when the Fenix have 2 power sensors connected - which will it use? (it is a hassle to remove the battery of the 4iii, as I use the bike outside as well).