I've dealt with a lot of rattlers, especially while I lived in the Valley of the Sun (the metro Phoenix area). Every one has ended up the same way - deceased! The means of achieving that ranged from .22s through .44 mags and 12 guage shotguns. Shoot the head, and don't get freaked out by the fact that the snake will keep moving for several hours after it is dispatched.
That is far too dangerous a snake to allow to inhabit your yard, it won't be too long before somebody is struck. They strike without warning far more frequently than after rattling - the rattling is a warning to possible threats that are far enough away to possibly cause a retreat, if you're close, they strike without warning. You are darn lucky the snake didn't strike you when you didn't realize you were in close proximity. They can, and do, strike from any position other than completely stretched out, and can effectively strike up to approximately the snake's total body length.
Oh yes, the one you photographed does appear to be a different snake; however, I would like to remind you that rattlers (Western Diamondbacks are NOT protected, BTW, despite what the snake-lover told you) are not solitary creatures - they live in dens, with numerous other snakes. I'll guarantee there are a LOT of additional rattlers in close proximity, especially since you have one (or more) breeding females there. My recommendation is to kill the snake, and kill every other rattler you see. If you live in town, and can't get away with shooting them, either use a long-handled shovel and decapitate it, or call the fire department (I don't know if they still respond, but they used to come out and kill them). Make sure you don't handle the snake's head after killing it, as the fangs still contain venom, and can do serious damage if you scratch your skin with them - definitely an item to be thoroughly disposed of.
Good luck, and keep your eyes open!
