My guess is that the people who write the sub-title text do not have an official spelling guide and sometimes have to guess how to spell unusual names based on how they sound. Hence the spelling of names can change because different people may either hear the name differently or hear the same thing but spell it in different ways.
For example, in
Bender's Big Score, when the Professor tells Bubblegum Tate that he doesn't think the equation of time can be solved, Bubblegum replies:
"[It] looks pretty damn solvable to me, Farnsy. Sweet Clyde, use variation of parameters and expand the Wronskian."
(Or at least that's what *I* think he says.)But on my copy of the DVD the word "Wronskian" is spelled "rhine skin" in the sub-titles.
Now, I had never heard of a Wronskian and certainly had no idea what it was or how to spell it but I found it almost as soon as I looked up 'variation of parameters'. Apparently the sub-title writer didn't do the same.
Futurama episode commentaries are where I found out how to spell names like
Lrrr,
Ndnd, and
URL.
As an aside, I have no idea why so many fan-based futurama sources seem to deliberately mis-spell the word
neutral.