I'd think it wouldn't hurt anything to have 2 regulators in line together. They are made to reduce the tank pressure so one regulator will be closed to give you the right pressure and the other one will be opened to maintain the right pressure so should still work fine Hooking two in series with each other. Hope that makes sense to you.
2014 Palomino Columbus 3650TH
435AH 12V VMax Charge Tanks, 520 watt Monocrystilline Solar Array, Morningstar MPPT TS-60 CC,Morningstar Remote,Cotek True Sine Wave Inverter,Cotek Remote Controller,50amp Progressive Hardwire Surge Protector
2015 Dodge 3500 6.7L 4X4
2011 CanAm Commander XT 1000