“Job’s story in Islam is very similar to the Hebrew Bible story”
Because it has been taken from the Bible story and then altered. Simple as that.
Taken from Wikipedia: http://en.wikipedia.org/wiki/Job_(biblical_figure)
In the Qur’an, Job (Arabic: أيّوب, Ayyūb) is considered a prophet in Islam. Job’s story in Islam is very similar to the Hebrew Biblestory but, in Islam, the emphasis is paid to Job remaining steadfast to God and there is no mention of lengthy discussions with friends. However, later Muslim literature states that Job had brothers, who argued with the man about the cause of his affliction.Some Muslim commentators also spoke of Job as being the ancestor of the Romans. Muslim literature also comments on Job’s time and place of prophecy, saying that he came after Joseph in the prophetic series and that he preached to his own people rather than being sent to a specified community. Tradition further recounts that Job will be the leader of the group of “those who patiently endured” in Heaven.
For our true story on Job, see:
Job’s Life and Times