Good thermometers should all match. I have three Kodak Process Thermometers, one of which is 40 yrs old, and all three are exactly matched.

All three of my light meters (Minolta Flash Meter IV, Flash Meter VI, and Autometer IIIf) all match exactly, not even 1/10 stop variation. I mention that because the joke about owning multiple watches is often applied to handheld meters too.