User blog comment:LuffyPirateKing/Luffy and his belly/@comment-4904935-20121023045451

Yeah Luffy's belly is not normal but personally I don't think he would be able to absorb more than one DF. I think Blackbeard was able to absorbed more than one DF because of his Yami Yami no mi fruit.

Luffy doesn't seem like the person to take short cuts, he ate the first DF accidentally, besides that it wouldn't do the series any good by giving character like Luffy two DF's. IMO it is overpowering! I would rather have him some kind of extreme power that comes from mastering his Gomu Gomu no mi skills than another DF! Plus, I doubt his haki level will remain the same throughout the next half of the series, So by the time he is ready to fight BB, Luffy will do just fine with one DF and improved level of haki.