Chang uses a number of pseudonyms, and in one orientation film, appears to have a handicapped arm (I think someone even said which arm it is changes, but I haven't verified). How 'bout this: There is a time loop already in progress. Chang knows and is doing a lot of travelling backwards, and starting to run into himself, a la "Back to the Future", like Locke. He (one of him) has apparently injured his arm in one timeline. So all the Changs are using pseudonyms to keep each other straight. Look at the line below which I pasted from his character page here on Lostpedia:
A key anagram for the name "Pierre Chang" is "Cheap Ringer". Definition: cheap ringer (slang) - inexpensive knock-off or imitation, copy of poor quality, deficient duplicate.
Can anyone support or debunk?