It appears that this is two different spellings for the same word.
http://www.merriam-webster.com/dictionary/requestor
However, if you search "requestor" on Dictionary.com, it doesn't find it. It only recognizes "requester". It seems that more dictionaries have eee-arr, and it may be the more common usage.
References:
http://in.answers.Yahoo.com/question/index?qid=20081118081010AAAOL1y
http://www.englishforums.com/English/RequesterOrRequestor/jcpz/post.htm
http://209.85.173.132/search?q=cache:WXMzYnSYJW0J:markmail.org/message/fqbujb73dqxcg3d6+requester+spelling+uk&cd=2&hl=en&ct=clnk&gl=us&client=firefox-a
-(theReal)Wireball(.com)
The normal spelling of the word is as shown "requester" (one who requests).Most dictionaries do not include the alternate spelling requestor.
The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.
No, the correct spelling isopportunities.
Tomorrow is the correct spelling.
The correct spelling ispreferably.
The normal spelling of the word is as shown "requester" (one who requests).Most dictionaries do not include the alternate spelling requestor.
The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.
No, "VAXINATE" is not a correct spelling. The correct spelling is "VACCINATE."
No, the correct spelling isopportunities.
The spelling employees is correct.
Knob is the correct spelling.
Opened is the correct spelling.
The correct spelling isfistulagram.
No, "surplussed" is not a correct spelling. The correct spelling is "surplused."
Tomorrow is the correct spelling.
"annex" is the correct spelling
Rainforest is the correct spelling.