Gaining Darkvision and how it works

[Burn56]

Okay, let's first state: everyone has normal vision unless specified otherwise.
If an ability grants you darkvision (or low-light vision), then do you gain the ability to see normally + the granted vision's spectrum?
If so, then that makes sense, because you have different types of vision.

For example I'm playing an Oracle with the Blind curse.
I can see normally out to 60 feet, but I can also see with Darkvision out to 60 feet.

I ask because if the answer is no, would gaining darkvision when you don't otherwise have it cause you to suddenly see in black and white (or heaven forbid, blind you in the daylight?)
Furthermore couldn't spells like "blessing of the mole" which grant darkvision for a duration be used "offensively"? I mean they are affected by spell resistance but have no saving throw.

Because of that spell itself, I believe that you gain your normal vision + darkvision, your vision just adapts to whatever environment you are in.

Thoughts?

[Starglim]

Darkvision no longer has a "spectrum" nor cuts out in any amount of light. It's a special ability that allows you to see even when there is no light (note that if you can't see for some other reason, darkvision doesn't give you an extra unrelated visual sense). You retain normal vision and benefit from darkvision if it applies.

In daylight your oracle can see to 60 feet in normal colour vision and doesn't need darkvision, but has it immediately if required.