Cadence metrics - cycling vs running

All the Cadence G-Metrix are labeled in RPM. Which is okay when I ride my bikes. But when I run, I use them but it sometimes does make me think "it looks weird isn't it?".

I can always clone and amend the label to SPM (steps per minute). But then the values itself are half of the actual SPM. Like, if I go to my Garmin Connect account, it shows my running cadence at 170 spm, but on video it shows 85 rpm. I guess that's somewhat true because it reflects the frequency of steps for one leg, as opposed to the actually number of steps take by 2 legs with spm.

I also suppose this is not a Virb thing, but more of how the data is recorded in the FIT file by the GPS watch? Or is it because I am not using a footpod, and my Fenix 3 is just getting it by itself? But even if its by footpod, you only wear 1 footpod, so it will only measure 1 leg.

Not really a biggie. I've been using the RPM cadence for some time with my runs. Just that it makes me think sometimes why its that so.

https://youtu.be/mYWza_HFDK4