Thanks for the suggestions!

The SetApp is detecting the dual meter somehow and only allows 2 options. Invertor or Invertor + import/export. I could set to invertor and move one of the two L1 or L2 over to #3 I suppose, but I would need both L1 and L2 data to make it useful.

The invertor seems to have a separate way to measure power, because I can remove the whole meter from the config and It still reports output. Also, the L3 production value and invertors production meter are different values, which probably shouldn't be the case...have not figured that out yet.

Anyway, for now I will use a z-wave power meter for home consumption and I can calculate the rest from there. Hopefully SolarEdge can report both values in the future.

Correct the inverter can show production without the meter, but the meter is a "revenue grade" option. It's more accurate. The inverter can be ordered with or without a revenue grade meter built in. If it's ordered with it comes with a special internal CT wired to the L3 CT input for the higher accuracy production metering.

For what's it worth, current SolarEdge systems seem to support both Input and Output values via modbus.
Tested with both the Inline Meter MTR-240-3PC1-D-A-MW as well as the Connection Meter with Modbus Connection SE-MTR-3Y-400V-A 100A.

Home Assist sensors:
modbus output in home assist

SetApp configuration view:
meter configuration in setapp

I think we can probably consider this topic resolved successfully.

At this point it has been a fair while now that the North American P+I/E dual-function meters (SE-RGMTR-1D-240C-B and -C) have been getting reported as two meters over external (SunSpec) modbus, one being "Hardware: Production" the other being "Hardware: Export+Import". (This does cause a spurious warning from the integration about a duplicate serial number, since both give the same serial, as they represent the same physical meter. It might be reasonable to suppress that warning for SE-RGMTR-1D-240C-* models.)

If users are not seeing both, I'd recommend they try updating their inverter firmware.

I'm not entirely sure what happens if they have a second meter installed. I'm not even sure if system normally tries to map the SunSpec meter slots to the meter's ID (1,2, or 3) or if it just puts each meter in the first unused SunSpec meter slot. If it does normally try to preserve the IDs, then users with multiple meters one of which is dual function might need their second meter set a specific id to keep it from overwriting the Export/Import virtual meter.

I'm not personally aware of any other meters that are truly dual-function like those. I suppose a 480 split phase P+I/E meter could be made, or a variety of dual function meters would be possible for places that do single non-split 240v. If such a meter does exist it might not show up as two like the North American P+I/E meters, but at least for those specific meters, I'm pretty sure this is just resolved now.

The inverter just maps meters to slots 1, 2, and 3 in the order they are discovered as far as I'm aware (possibly address order).