A WP of 6500K is a range of colors, it isn't an exact specification. Further, your Spyder package may have a 6500K setting, but another package with an identical setting will not ensure the same WP. I know, in a prefect world it would. You can set the WP to 6500K (which isn't the same as D65) but keep in mind, this might produce a visual match to someone else's display with the same setting, might not.

This might give you a better idea of what the various calibration settings do, why and when to set them:

http://www.luminous-landscape.com/tu...too_dark.shtml