Can we talk about a BASIC UNIVERSAL simple PV kit for preppers.

[Skvez]

In order for the regulator to know the state of the battery, every so often it stops charging briefly and reads the Voltage of the battery.
If you have multiple regulators feeding the same battery bank what can happen is regulator A stops charging and reads the battery but sees the PV Voltage from regulator B rather than the actual state of the battery and believes that the battery is fully charged and stops charging.
I'd advise you oversize your regulator, you can add more panels and more batteries but I don't advise trying to feed multiple regulators into the same battery bank.
Of course you can get multiple regulators to feed multiple (separate) battery banks. That gives you redundancy and we preppers do like redundancy. It a little more awkward when it comes to loading as you need to distribute (or switch) your loads between your two or more battery banks.