Phred, my '88, came with four keys - two keys with the VW logo and a black
plastic insulator around the edge, a bare-bones, uninsulated key, and a
gas-cap key.  The gas-cap key is self explanatory.  Of the remaining three,
all will open the doors and hatch and work the ignition switch.  However,
only the two with the black plastic edging will open the glove box.  I
admit this may not be a factory thing.  But, I had the exact same thing
with a '88 Fox GL Sport I owned, and several Rabbits I've also owned.  The
only difference was that the ignition key - the ones with the black plastic
thingy - opened the gas cap as well.

YMMV...

Alan Bosch
& Phred ('88 Wolfsburg)
Rochester, NY

Bumper sticker:  Visualise Whirled Peas