I'm wondering if you have to double check the temperature and humidity settings on incubators with independent tools to measure this? If so does anyone have a temperature or humidity gauge that they could recommend?
Yes, it's good to have at least two thermometers. You can get away with 1 hygrometer, but I'd suggest you do the salt test to see how accurate your hygrometer is.
If you use the search function you can find links to the salt test and also several threads with suggestions and links for thermometers and hygrometers.