For cyclocross, double toe clips were used. Simply because these were stronger and more durable. Example: you approach an obstacle like barriers, stairs, a steep hill or sand. You have to get yourself ready to jump off the bike. With your feet into the clips, it's impossible to jump off quickly, so you will stand with one foot (usually the left foot, in case you shoulder the bike on your right) on a pedal. The other (right) leg between (left) leg and bike. But because you stand on the bottom side of the pedal, the toe clip hangs down and can easily scrape over the path of road surface and even hook up with a rock, root or branch. This may bend, break or at least wear the clip.
Double clips are some kind of added security. Your toe clips will not bend or snap during a ride or race.
Christophe supplied double toe clips as a standard item, see photos. In case you couldn't get any (fitting) double toe clips, you could (can) also make a pair by yourself. All you need is 2 pairs of
regular toe clips and some rivets (from a hardware store of Mr. Minit shoe repair). Drill out the rivets of the toe clips to remove the eyelet for the toe strap. Then, put 2 toe clips together and put the eyelet on top of it. Finally, connect the both clips and the eyelet with rivets, using a hammer or bench vice (original riveting tool is also possible, but I never used that).
