Counterfeit 7400 logic?

Just ran across an interesting oddity -- I ordered a few 7475s to replace the ones with corroded legs on my Imlac's memory control boards; upon replacement I note a dead short between 5V and GND (as evidenced by the 5V supply being drawn down to 1.5V or so on powerup). After pulling the chip out, it's pretty clear that pin 5 (VCC) is shorted to pin 12 (GND), as are pins 4 and 13. Verrry odd. I grab the other replacements I ordered and they test the same way. My curiosity getting the better of me, I break the top off the chip (not entirely successfully). You can see the results here: http://yahozna.dyndns.org/scratch/imlac/fake7475.jpg The picture's not great, but you can see that pins 4,5,12, and 13 are connected to asolid piece of metal! There does appear to be adie in the chip, interestingly enough(not pictured). Defective chip? Other chip relabeled to be a 7475? Who knows... Unfortunately, I can't find the invoice for these items (I ordered these a couple of months back), so I don't know where it came from; it was probably either Jameco or Digi-Key... Ugh, I wonder how many others of these chips I ordered are fakes... - Josh