fwiw, I find designing multiple up leads to more complications than it's worth. Unless you're going to be doing the final press run, you're effectively trying to impose these cards to early.
Consider doing the merge to a business card size document -
You won't have to meddle with the multiple records per page dilemna .
You can send proofs of the cards as designed at actual size.
You'll eliminate redundant stories and graphics. (The logo stays on the master page in my bcd files. You will have 10 - 100 + instances of the logo in you file. Thinking about it, I'd leave it out of the merge source doc and drop it in the final merged document on a master page)
Future runs are not going to entail the exact qty's and persons (99% certain on this).
Occasionally, not all the persons in company are going to receive the same number of cards initially; Sales staff may receive double the qty as HR and the shipping clerk.
You're not going to have crops marks for these cards. (You could merge 2 wide by 5 down to a 7 x 10 document and print that with crops or add crops after the merge of course.)
It's been a long time, but I'm not fond of grouping and picking apart stories and graphics for cards from a final imposed document for reprints. Rather, I have BCD files that have one page per person, and the source file or pdf proofs get imposed as needed.
Just my thoughts, I manage many business card documents.
This forum can get you over a standard merge document or a mutliple records per page doc in half a day.
I did a three-part tutorial on Data Merge a few years ago on InDesignSecrets.com:
Michael Murphy did a good videocast: