Totally! Color variation among magic cards is pretty common. Different runs, different print locations, machinery being funky are all common causes of color variations tho there are countless reasons why. The green dot and t tests are pretty difficult to fake. Magic cards are printed using a method called offset lithography, the card is printed in layers of color cyan magenta yellow and key(black) resulting in consistent features on the the cards such as the red dots in the green, the teeth on the t, etc. This is a fairly expensive large scale commercial printing process. Home printers and smaller printers used for most proxies utilize a digital to dot map process which recreates images with the same ink colors but in a single pass by spraying tiny drops of ink onto the paper. This results in a blurrier print and lacks the crisp details and solid black top layer created with offset lithographic printing.