Arizona is a rear only plate state, but when I got personalized plates, I was given two plates. (three different times) I guess the extra is a spare if someone stole the original.
Also, (hijack attempt) when I lived in Texas, they had a big problem with the stickers for each year being stolen by people without the means or desire to pony up the fee each year. So you had to be careful if you parked in a shopping center during the first week of the month. (Really bad in the Dallas Area) Don’t know if they have minimized the problem since I have been out of Texas for 10 years now.
it’s quite simple. if a car is coming towards you you have a chance to read the numberplate before the car passes and you end up looking at it in your mirror in reverse.
Even if nobody cares in Alabama, the same may not be true in other states you drive through, especially two-plate states.
For instance, suppose you slapped a Texas plate on the front. The next time you go there, the cop sees a plate which hasn’t been used in the Lone Star State for two or three years. This may be illegal, even if you’re registered in another state.