I always questioned the first sign as there are many for sale in that color combo. However I have seen that same color combo sign for sale on this site several times and no one questioned authenticity. That just added to my confusion, again on that first pic only. Some say it was a later pump plate, but they are always white on the back versus the greenish/gray color of the known originals.
Here is an original white back round sign. It is the "regular" gas sign. The above fake says "Super Extra". The original "Super Extra" has a red back round. I do not know why they faked it this way because the red is more desirable.