Is it best for faults to be fixed by the original programmer who wrote the code? Or is the programmer who discovered the problem better placed to make a fix?
It's always helpful to approach any problem with a fresh pair of eyes. When debugging, this method avoids the common problem of a programmer reading what he meant to write, not what the code actually says—too many bugs stay hidden that way.
On the other hand, the original programmer is probably best placed to make the fix. He understands the code inside out (hopefully). He knows what repercussions a particular change will have. He'll be the quickest to pinpoint the location of a fault.
In Real World organizations, the choice of who makes a fix may be determined ...