In some of the
stories about Sherlock
Holmes, Dr
John H. Watson is referred to as James Watson. The
reason for this is unknown, but one theory is that the good doctor
used the name James when enrolled in the military.
This is not the only discrepancy however; it seems the wound that
ended Watson's military career has a tendency to move
around. In A Study in Scarlet he mentions that he was hit in the
shoulder, while in The Sign of Four he is experiencing pain from
his war wound in one of his legs. In The Adventure of the Noble Bachelor a wound is
mentioned in one of the limbs, but we don't know which.
This is of course cirumstantial evidence, but it seems that we are
not told the whole truth about Watson. Maybe he has an evil twin who
sometimes manages to upstage him?