Can I feed a 200 amp sub panel from a 200 amp main?

First off, why not pick an appropriate title. This is the electrical section so we know the question will be about electrical.

You can by code, by physically and correctly might be an issue. You would need to get what would be called a sub-feed block or something similar. This is a terminal block that snaps onto the panel buss just like a breaker, but is just a set of terminals for the wire to connect to.