There were two different chips made and released at the same time.
The difference
1. Had Ltd 250 on it and Ungar spelt correctly. All of those chips survived.
2. Had no Ltd on it but 2,500 were made with Unger spelt incorrectly. Most of the chips were destroyed.

Now before everyone else chimes in, you are talking about the 1999 chipco chip and everyone else is talking about the Bud Jones series of chips.