The top one "Lambda 1" doesn't shift from 4.14v
The bottom on starts at 1.82v and then goes down to 1.75v

Doesn't look right to me. But then again I don't know so that's why i'm asking. :-)

Is your LPG connected to the vehicle lambda sensors then? Guess it must be or you wouldn't get readings!
You might see voltages like that on a GEMS, which has 0-5v lambda sensors, but not on a Thor which has 0-1v sensors.
Maybe your LPG software/ ECU hasn't been given the correct information in the setup (on mine you have to enter the lambda sensor operating voltage range)
I don't believe the lambda readings in the LPG actually do or contribute anything apart from information on the screen, so it's not a problem in itself.
To get the right lambda readings you need a reader that will read them from OBD2 and will actually tell you what the car's seeing

that and they should constantly flick between lean and rich when everything is working correctly.

Yeah on my software you enter the range. Simon did it. Perhaps it's wrong? I'll plug it back in tomorrow and check.

I have an elm obd. Should be able to get Lambda info from that shouldn't I?

Should do

Lambdas reading ok on OBD so must be either on the wrong setting in the LPG software, or not connected to it at all.

Software needs to be told you've got 0-1v lambda sensors. Then you can check to see if the readings from the elm match what the software is showing. They may not be connected, the LPG system doesn't need them to be, it's just convenient to be able to see them on the screen rather than on a separate code reader.

If OBD live data reads correct and flicking lambda voltages but LPG software doesn't, the LPG ECU isn't connected to lambda.. it doesn't need to be connected to lambda.