The number plate might have been transferred to the vehicle by a previous owner, as you can do in the ACT. Might have been a previous owners initials, or just interesting because of '302' (for a Falcon v8). And even then, number sequences get out of the expected sequence, as they did in the ACT for some unknown administrative reason (whole sequences missed e.g. YKa-nnn appeared after YLa-nnn). Who knows after 40+years. Not important unless the owner is claiming 'original VIC rego from new'.
And the rear window sticker might simply have been on a replacement piece of glass. I have no idea where my own rear window came from, other than the bundle of parts when I bought my "shell + parts" as a package.