Hey there..
I have a few duplicate Vic-20 (Commodore released) carts I was looking through and noticed a variation in the labels - some labels seem to be brushed aluminum, and the rest look pretty much generic. On the generic looking ones, there are also variations - Gorf and Avenger have different fonts, for example.
After exhaustive searchies the only place that seems to mention label variations for a system is Atari Age. Did the label variations mean anything? ie. released at a certain time?
I don't have any pics now, but I might be able to post some tonight if it would help.