Sensors are generally slightly less accurate than blood testing meters and blood testing meters are allowed to be up to 15% out. But if you compare the sensors against the glucometer you should get an idea of which is more accurate, though there is a slight lag in a sensor reading so I wouldn't do the comparison when your bg is changing rapidly.
As a T1, I get insulin induced hypos and use my dexcom to avoid most of them (it alarms at 4.4) If I have a bad hypo, goes below 4 steeply, I get out my trusty glucometer to check when I go back up. I find the dexcom generally matches it pretty well, but sensors do occasionally misread, so you can't 100% rely on them. Note the dexcom allows you to calibrate your sensor if it seems to be reading low or high (mine often gives me false hypos when I first put it on, reading slightly low).
You'll learn your own body and how accurately either cgm works with it, but I'd always believe the glucometer over a sensor, though I might take a second reading (wash hands etc) if the two wildly differ.
Good luck, I'd be fascinated to hear a break down of how the two cgms compare when you've finished the trial. (I used to use the libre 1 but had to stop because of an allergic reaction. I much prefer the G6 but haven't tried a libre 2 so don't know how much it has improved.)