I'm looking to repaint some cabinet hinges with spray paint and I want them to really last. Would the idea of using primer spray paint and then a primer+paint spray paint in one after, make it longer lasting?
I'm using metallic spray paint so it wouldn't use a sealer after and that's how I came up with this idea to prevent chipping. I also already used TSP to clean them and they are fully dried. Any disadvantages to a primer and then primer+paint? Any other steps/recommendations?
It always depends on the specific products. The topcoat having primer isn't really a benefit if the base primer provides a strong bond anyway. (It doesn't hurt).
The real question is how hard the topcoat will be and whether it stands up to the movement of the hinges and any cleaning and impact abrasion.
Read the label on your base primer. It may suggest scuffing the metal to get a good bond. Remember that more thin coats are better than fewer heavy coats, both for appearance and durability.
Painted hinges never look nice, unless it's a decorative piece (non-functional). Whether you apply the paint with a spray or a brush, it is inevitable that some paint is going to penetrate the hinge. This will either cause the hinge to bind, or the paint to scrape or peel off in bits.
If you are happy with that look, then its fine, go ahead. Otherwise look for a pre coated (anodised or electroplated) hinge.