FWIW I've been told by the owner of Hutch Mountain, maker of a propane conversion kit for EU2000i's, that the entire inverter logic control board is "different" in our older EU2000i's (I've got 2 of 'em).
For
that purpose the cutoff is SN's
lower than:
EAAJ-2017305
EACT-1000001
(I've got EAAJ-1171xxx and EAAJ-1258xxx)
I didn't ask for a detailed explanation, but whatever the difference it renders the older units unsuitable for their propane conversion system (and also is cost prohibitive to attempt an 'upgrade' per Hutch Mountain, so I just decided to 'pass' on the propane conversion and stick with the gasoline that has served me well for so long).
My EU2000i's are bulletproof trusted units, both being 'old' they run great paralleled with each other. One will pull the small AC OR microwave on my Casita but the pair run much more relaxed and quieter with the AC load, use less net fuel, and allow concurrent AC+microwave operation. I do run 'em on an extended tank, often 4 days non-stop in the generator-friendly motorcycle-racing paddock during hot-summer race events.
I'd be loath to risk 'letting out the magic smoke' in your situation, whether it be in one/both inverters or a device driven by same, but YMMV / 'No Guts No Glory'