Have you taken the Myers Briggs Type Indicator more than once? If so, have your results varied in any degree?

Amidst a discussion with a friend yesterday regarding the accuracy of the Myers-Briggs test, I took the test twice in under an hour. My results in letter form were identical – ENFP – but the numbers that indicated the strength of my preference for each were drastically different. How valid do you think the MBTI, and other similar personality index tests, are? How accurate do you find your results? I have taken different versions of the test, but gotten consistent letter result. Do you think the specific test is influential? Do you think your mood at the time of the test is influential? Would you consider taking it more than once having expectation bias in the sense that you may be more in tune to which answers applied to the type that you were the last time you took it?