I emailed sonicwarp to see what they thought about the typo. They didnt beleive me so i emailed them a pic.
heres wat they said - from
andrew@sonicwarp.com
Wow, that Isis is going to be worth a few pounds in years to come !
The engraving machines we use are computer based, and we have noticed that sometimes the number or word that is coded in the computer doesnt get translated correctly through the engraver and thus when it should have engraved a letter R it actually engraved in your case a T.
I have not seen this before on another isis, but we have had a few key and isis numbers engraved with mismatches from the computer
Hope this explains things
Best Regards
Andrew