Andy_Langton - 7:19 pm on Apr 18, 2012 (gmt 0)
The alt attribute is a way of describing the contents of an image to those that are unable to "see" it, visually. Any serious webmaster should be using it, and using a blank (alt="") attribute when an image does not convey anything useful, but is for decoration. You will fail pretty much every accessibility test without correct use of alt attributes. A search engine will treat a trustworthy alt attribute the same as any other text on a page.
A title attribute is intended for additional information that you may have about any element of your page (it is not related to images at all) and, to be blunt, is not something you are likely to use with any degree of frequency on a site of any size - it's just too much effort for too little reward.
That said, there is never any good reason to have an alt attribute and title that are the same. The alt is only useful to those that can't see the image!