Many first time stand up paddlers ask, or simply joke that the paddles should be double ended. Their theory is that a double ended paddle would put a stop to their wonky paddling track and keep them paddling down a straighter line. While this is true, in the same amount of time it would take them to go down to the local shop and buy a double bladed paddle, they could have better spent the time learning proper paddling technique which achieve the same outcome of paddling in a straight (ish) line. Plus they'd be up $400, and they wouldn't look like an outcast at the beach. But do students listen? No, they bring up the fact that you should (in theory) be able to paddle faster with two blades. 

Is that right? As usual, it all depends on who you ask on the internet. Some say that the quicker recovery time with a double bladed paddle maintains speed better, equalling a faster overall speed. Others say the extra power you can generate from a single bladed paddle outweighs the slower recovery time. And an overwhelming majority cite that a single blade tends to be more comfortable when sitting or kneeling in a paddle craft. Google it for yourself if you're interested, but at the end of the day, time will tell whether stand up paddling warms to the idea of the double bladed paddle. We might be laughing about single bladed paddles in 10 years time, when every SUP board gets sold with the 'Power glider with DRG' paddles.