Well I think I found my problem, apparently HID makes several versions of the "World Tag" and the one that I bought is chip type "Titan" which is a 1024 bit EEPROM. The ID-12 from SparkFun can only read 64 bit:
http://www.hidglobal.com/sites/hidglobal.com/files/resourcefiles/hid-rfid-world-tag-family-ds-en.pdf
I am surprised that Parallax does not offer this datasheet on their website. So for anyone interested in using these tags from HID with the readers from ID Innovations that our offered at SparkFun you will need the "Unique" world tag. I wish mfg's would make it simpler on pairing tags to readers -- AND -- specify not only the air interface protocol but also the encoding.
I hope somebody finds this useful and good luck finding a distributor!