Here's what I've been able to figure out so far... but I'm still confused
Say I transfer 100 btc from my wallet to another address.
I know when creating the transaction my wallet will spend all from every transaction to get me the 100 btc. Anything over the 100 btc will be returned to me.
So I have my prev_out totaling 102.625 btc.
I send 100 btc and it goes to the correct address.
The 2.625 btc gets returned to me, and my wallet shows it available, and listunspent shows it available.
However, when I try dumpprivkey for the new address that the 2.625 btc was sent to, my wallet tells me it's not known. Why?