why did blockchain.info misstate the value of this transaction
The input and output totals claimed by blockchain.info are correct.  But the BTC 0.00973 output is presumably going back to another address owned by your wallet, as change.  Blockchain.info has no way of knowing which output is the "real" destination and which is the change, so it reports the total of both.

SatoshiDice knows which of the two outputs was sent to it (because it controls that address and not the other one).  So they only report the amount that actually went to them.  

This has nothing to do with whether or not the transaction is confirmed.