Ha, getting two books doesn't quite add up, imho. Now buyers have electronic version, and they can sell all those hardcopies to people who don't want to pay full price, so theoretically you're undercutting your own sales. I'm sure it's by no means one-for-one, but could be significant issue. Instead of telling somebody about a great book i read that they should buy, or i might buy them as a gift, i already have this extra book i got for free that they can have. But maybe it works out.