Most of the (scientific) conferences I've been to already have the paper-in-plastic-sleeve badge kind, and universities are very stingy, so I suspect it's the c

Most of the (scientific) conferences I've been to already have the paper-in-plastic-sleeve badge kind, and universities are very stingy, so I suspect it's the cheapest possible version. Very often you already have extra info in there, like a slip of paper with your individual Wifi access information. The only extra cost to having this two-sided is printing the name slip twice instead of once, and I that should be negligible. A little extra paper is certainly cheaper than lanyards with two attachment bits for the two attachment point version (that can still flip).