Although the exact number of revisions is unknow, we know the process the original version that Jefferson wrote went through.
Jefferson wrote the vast majority of the Declaration himself, although he did borrow heavily from philosphers of the time such as Thomas Hobbes and John Locke. Jefferson then presented his first draft, which may have undergone several revisions made by himself, to a small committee of men appointed by the Continental Congress to write the document. The first two men to look it over and adjust the language where John Adams and Ben Franklin. These three submitted it to another pair of men, Robert Livingston and Roger Sherman, both of which emended it as well.
After this first pass, it went to the congress itself where still more changes were made. An entire section of slavery was deleted after Southern delegates threatened to leave the congress. After a few other minor changes it was approved on July 2nd.
Unknown really, when any author produces a work, he or she may scratch out and rewite certain words and or phrases, just like a poet does.
The final copy submitted to Congress by Jefferson was revised also with X # of additions/subtractions by the Congress. He was simply the Principal author.