Chris G. of Carbonerro has designed a double ended paddle for stand up paddling. Check it out, pretty cool. http://www.carbonerro.com/el-doble
Double ended stand up paddling has historically been called Striding. Jeff Snyder has been doing it for years on an inflatable kayak and is usually seen going off waterfalls. Fletcher Burton began standing up on his waveski in the late 1990's. And Israeli lifeguards have for years used the double ended paddle on super wide SUPs. Read more about Striding in this Canoe Kayak Magazine online article, Here.