In Drupal 7 we imagined that we would use blue buttons whenever there are two buttons shown. This to make the primary one stand out more, and thereby help the user be more efficient. This all comes from the principle of adding appropriate visual weight, by using the 'blue' for the primary save action we allow the user to be a moment faster by determinate the right button not by label or placement, but by color.
There is quite some practice and theory behind this, a good starting resource on this can be found at http://www.lukew.com/resources/articles/PSactions.asp
I have identified a few places where this occurs:
This is dependent upon
PASSED: [[SimpleTest]]: [MySQL] 48,282 pass(es). View
FAILED: [[SimpleTest]]: [MySQL] 48,208 pass(es), 2 fail(s), and 0 exception(s). View
PASSED: [[SimpleTest]]: [MySQL] 48,005 pass(es). View
FAILED: [[SimpleTest]]: [MySQL] 47,982 pass(es), 4 fail(s), and 1 exception(s). View