We have stumbled upon the answer, completely by mistake.
While in the process of getting the tapes replaced under their life-time warranty, we were on the phone with the different manufacturers. While Sony agreed to replace all tapes without batting an eye, Fuji took a different stance and gave us the answer to our dilema. According to them they would take a sample of 10 tapes and check them over. If they were found defective, we could send them the rest. However, if it showed on the tapes that there was a registered checksum bit added to a certain track, then they would return the first ten, bulk-erased. When asked about it they stated "any DLT1 that has previously written to a tape (meaning the older DLT drives) had very strong magnetic heads, and wrote to a track that the newer DLT drives do not write to anymore, but they DO READ THEM. IF there is anything on this extra track, no matter what the location the drive finds it on the tape, the drive will see it and automatically refuse to write over it."
The older drives had stronger write heads, that were done away with in newer models presumably for cleaner more reliable data. However, the new drives are just not capable of overwriting this additional track. The older drive marked this track as an identifier throughout the tape, like an extra parity bit from a 14.4 modem. We also discovered to our chagrin that these tapes will not be erased completely even if you pulled the tape out of the casing and ran the radio shack bulk eraser over the film. Apparently the writing is so strong, you have to use an industrial strength bulk eraser costing anywhere from $00/rental to $50000 to purchase.
I hope this helps someone else out there. Thanks everyone for your help!