if I send out say, two of them one after another, is it still the random Tx "ID" that makes it win or lose? I guess it sounds like it's always better to do a single bet than try grouping anything, correct?
If you send them one after another, then they are completely independent events.
What you can do, however, is send multiple bets *at once* by clicking 'add recipient' on the satoshi client's 'send' tab. If you do that, then all your bets in that transaction get the same lucky number.
The lucky number is determined completely by just 2 things: the transaction ID of the transaction containing the bet, and the day's "secret". If you send your bets separately, they'll have completely different transaction IDs, and so their lucky numbers won't be related.
It does appear that 'luck' runs in streaks though doesn't it. I have to believe that's just an illusion though - that we focus on winning and losing streaks and ignore the win/lose sequences that are less patterned.
