If you have two scripts from different doctors for the same controlled substance for the same condition, within overlapping refill periods, that is what is illegal (though the laws and penalties vary).

Are you getting the same drug from both doctors? Do they both know about it? Is it within the same timeframe?

The reason you're asking this question is because you want to know if it's legal or not, not to see if what you do amounts to a term used in drug slang. Doctor shopping usually means visiting multiple doctors to get the same drug or type of drug concurrently, for the purpose of supporting a habit. Regardless, it still may be illegal.

-yawkaw