curious am I .
I only see one temp sender, on the head ,at the back in the online drawings.
Maybe it'd defective or the gauge. usually you remove wire from sender,ground it and meter goes 'full scale'. WSM should have 'how to test sender'...so many ohms when hot and cold.
it'd be nice to know what the other one is and for !
Until you KNOW, if you use the tractor keep a nose out for 'high heat ' smell ! Also, check fan belt tension. If it's a little 'loose',pump won't pump coolant and engine can overheat, then big $$$$$ to fix.