You may getting "accounts" mixed up.

You can have one iDine/RN account per airline (or hotel program, etc): UA is one RN account, AA is another RN account, etc. At "1 visit per month" places, you can do one visit per RN account.

But each RN account can be linked to several credit card accounts. That alone doesn't get you anything in terms of overcoming "1 visit per month".

However, there's one other way you may be able to overcome "1 visit a month" with just one RN account: If the restaurant has gift cards or gift certificates, and if you can buy a bunch of them as one credit card transaction*, that can be your "1 visit per month" for a much larger dollar amount (earning you many more miles), and then you go back to that restaurant using those gift cards or gift certificates for the rest of the month (or subsequent months even)! (*Just make sure they won't ring each gift card/certificate up as a separate credit card transcation that you sign; if so, it won't overcome "1 visit per month". And remember the $600 per month overall limit at ost restaurants...)