If you live in a 1 plate state, and that plate are in the back, your only chance of getting a plate capture on a oncoming car that do something naughty will be with a rear camera as he/she have passed by you.
Using 2 similar cameras, with the same settings mean you should still have the footage in sync as the startup / boot time on both cameras should be the same, only downside IMO would be you have to go to 2 cameras to get footage if you need footage from both cameras that is.
Many of us started out with 2 - .3 - .4 single cameras in the car, that would be us addicts, you can also sync footage with a video editing program if you really wanted to ( for sharing ) in a dispute in a court, well you will have to submit clean unaltered footage, but if its a little out of sync i would say thats the courts / insurance companies problem, but with video, and a time/date stamp that should be a no brainer.
In the +10 years i have been into this, and sharing idiots in traffic on youtube,most of the times they have always performed on the front camera, if i have added rear or side cameras to my footage it have been B-roll footage.
Mind you i have been hit in the rear 2 times where my cameras did not get it, but all my fault, first time rear camera on too long and cheap USB wire with power from the front, second time was while parked where i got hit 2 hours after i parked, but only used parking guard for 1 hour on the build in timer.
A front camera alone, well it 100 % document what you do, so if you get rammed from behind and the the 4 occupants in that car said you changed lane suddenly, well your front camera will have a recording of you driving rock steady in your lane, right until BAM ! So their coordinate lie,,,,,, fended off, even if its not on camera.
I lean a lot on that fact myself, CUZ it dont take much before plate capture is not possible, and thats also fine, that is unless you are the victim of a hit and run.