I've been setting up the chokes on my twin Solexes - these are the standard 2 litre fitments as far as I know, apart from possibly one feature. Here is the inside of the left hand bimetallic strip: Compare this with the right hand mechanism: There's an spring added to the outside of the bimetallic strip on the left. I'm curious why this should be so. Comments anyone? As far as I can see the bimetallic strip expands and uncurls, allowing the choke flap to return to the open position. It's not driven into the open position by the bimetallic strip - there's a spring attached to the choke spindle that does that. The bimetallic strip is there to close the choke when it cools off, and to slow down the opening. By rotating the mechanism slightly the timing of the choke flap opening can be advanced/retarded to suit weather conditions.
As far as I can remember (it's been a couple of years since I rebuilt mine) both mine are like your right hand one
I've looked inside a number of Solex carbs and this is the only example I've seen like this. It's a genuine Solex but the whole carb was replaced new in 1993 on a trip to Spain, according to the papers I have. The choke unit is serial no. 109LI, and the other side is 110RE.
