dan is quite correct. you can use blades as a pair of paddles.
the good :
- it brings less water into the boat.
- ii is faster for a little ways.
- it might weigh less
- you can do spins like a maniac.
- if terrified, one can sprint a few yards in an astonishingly short time
the bad :
- it is much slower over a long distance
- it does not look at all cool
- you can't brace worth a hoot with half a paddle.
- all the good people use one paddle.
if you go the 2 paddle route (as does peter), be sure to FIRMLY TIE THEM OFF. paddles will sink like a rock, and then they'll be gone.
there are yins and yangs to the one vs two affair. i have had good fortune using the two paddle method for years, but all i do is cross lakes/rivers and float easy rivers the direction they are going.
crossing a wide river (mackenzie) or working downriver into a headwind (very small whitecaps) will soon enough exhaust the most determined paddler with a pair of blades.
if thee is upon ice, and the going gets sketchy, one needs to "scooch" over the questionable sections. this is exhausting in the extreme, and it takes the pair of blades to do it.