Here's another approach, assuming your state allows repainting yom plates the same colors as when new if needed and otherwise in good condition.
Do a little experimenting on something small before going whole hog... You'll need fiberglass cloth, resin, release compound such as thick cook pan spray, and paint. Apply release compound to the plate you wish to duplicate, cut a piece of fiberglass cloth a little bigger than the plate, saturate it with the mixed resin and lay it onto the face of the plate, pressing it down around the numbers so there is a good contact. After it cures remove the fiberglass from the tag and; viola, you have a female mold to use to duplicate the tag. Employ the same process and materials as in the first step. When cured separate the pieces and carefully trim the duplicated tag and paint it. Last step is to shrink wrap the two tags back to back. Both sides will be visible, look identical, and the DMV probably won't require unwrapping them for further inspection.