This will probably be moved to the iDine topic.
http://flyertalk.com/forum/forumdisplay.php?f=400

There's a lot of information there. Almost all iDine restaurants have either a $600 or $1,000 monthly limit (be happy it was the latter). If you split it between two cards for the SAME iDine account, I'm sure they'd be able to tell. However, if you have two separate iDine accounts (with separate AAdvantage numbers) then you could most likely earn 10,000 miles on each aadvantage account. I'm pretty sure they don't allow two iDine accounts with the same AA account linked (they also don't allow one credit card linked to two accounts)

(iDine = Rewards Network)

one more thing... did you dine on or before 12/15? If so, make sure you RATE the restaurant... you may get an additional 5 miles/$