Help, I keep trying to find the answer to this. Why cant someone send in a huge amount of work that they have already submitted to another pool. How does GHash.io what (Non-block find work) I have submitted to bitminter and vice versa? Whats to stop some clever coder from submitting non-block finding work simultaneously to multiple pools?
Work valid for one pool would not be recognized as valid work for any other pool. There are a couple layers where this is enforced, but the easiest to understand is that the hash that you work on contains a transaction paying the pool's address 25 BTC for the block. A different pool wouldn't accept work paying someone else. This is the same reason you can't intercept a valid block solution and pay the reward to yourself.