OTOH, some asteroids are oblong or misshapen, and in those cases probably began as two (or more) asteroids, winding up giving each other the come-hither, until they became one. Of course, a smallish object crossing their mutual path at the right velocity could knock them apart as it was vaporized by the impact.
for examples:
4179 Toutatis
1620 Geographos
http://www.google.com/search?q=near+earth+asteroids+oblong