Yes, you can repeatedly clean, sanitize, and reuse the caps until they're worn out- which will take quite a bit of time if you're not too rough on them. You can also clip off the tamper-evident ring and use without it.
However, the inner seal will eventually wear out, and sometimes you don't realize until it doesn't hold pressure anymore- so when you cap, squeeze the bottle a bit and make sure there is a hard stop- if beer comes out, so will CO2. (you can also squeeze out the oxygen before you completely close the cap- the bottle will re-expand with CO2 later- something you can't do with glass!)
They're also pretty cheap to replace at many brew shops... so many people just toss the caps and buy new each time to remove one more worry...