Ooops, khuon beat me to it

Both of those Shimano models are one-sided, yep. The Speedplay X-series road pedals are double-sided, very light, and have extreme corning clearance, but they also have a very free-floating feel that may take some getting used to.

You might consider some mountain-oriented pedals as an alternative. I like the Shimanos for their durable ball-&-roller spindle bearings (not ball-&-sleeve like many of the competitors' pedals), the heavy-gauge metal claws, and the ease of finding cleats. You'll give up some cornering clearance and add some weight.

Between the two, I can clip into my Speedplays more easily than my Shimanos.