You can see on the sensor below that there are two inputs. One is for a gauge one is for a warning light. So it is doing two different jobs in one sensor. The warning light part is a simple switch, in this case it will switch at 98C + or - 3C. When the switch is open the light is on.
The other pole is for the gauge and dose a different job. This pole senses temp and gives a known resistance depending on temperature.
This resistance is what your gauges are measuring.

So do you connect one gauge to each tab - no.
Will two gauges work off a single sensor? Yes should do in the worst case you can use a switch-over relay at the fly bridge for when you are up there.

All gauges and sensors work in the same way - however they are not all compatible.
Each sensor is designed to 'sense' a value range and send a value to its gauge in OHMS. 
So they all do the same thing - in the same way - however each manufacturer makes their gauges and sensors with their own set of values. There is not industry standard.
When you purchase a gauge it will have information on the operating range and THE INPUT RANGE. 
When you purchase your sensor you need a matching set of operating and input range or the gauge will not function correctly.
The best way to be sure is to purchase both gauge and sensor from the same place.