On a 2wd the sender near the turbo is for the temp gauge reading, the other one for the ecu is at the rear of the head on the nearside, but only one for the gauge.
So long as fans cut in and bring temp down enough to cut out again, nothing to worry about, my own gauge has a mind of it's own.
I do notice that it does indeed take a long time to bring the temp down after fans have come on, I removed the deflector between intercooler and rad and it helped 500% in this respect.
tabetha