Temp sender question

[2MEKE]

I'm going to put an aux temp gauge into my little brothers Surf (LN61)for him.
I'm assuming that one of these senders is for the factory gauge?...but when I removed both plugs the temp gauge stayed smack bang in the middle! Another design 'feature' maybe??
Seriously tho, why does it have 2 temp senders?
And does it matter if I remove one to fit the new gauges sender?....Which one should I remove?


"B" has a yellow wire that disappears down behind the injection pump.
"A" has a green wire that goes to here...

[scs]

earth out both wires, whichever one has an effect on the temp gauage is the one you want, make sure the ignition is on btw . if this fauls I'm pretty sure its the yellow one