Say for instances, I wear my Fenix 2 on let hand, and have it set up as a daily activity monitor (Steps, cal, dis). Then on my right hand I have my vivofit.
Say, I decide to swim 50 laps, I'll actually take my vivo fit off, use the fenix 2, then roll the fenix 2 right back into daily tracking. I'll then pick up my vivofit. And move on with life.
This is just an example btw:
Say I sync both to connect, it will only take the vivofit's steps as the actual daily steps and distance. It's like it doesn't even recognize the Tactix/Fenix/Fenix 2 ability to act as an activity monitor. Although, if I sync just the fenix it does load up the steps taken and calories, etc...
Basically, it needs to load both stats, figure out what you were doing (in case above swimming), then take the Fenix 2's steps over teh vivofits since they were used from in pool to out of pool