Frank
They didn’t put it on both as having it on one allows you to leave it attached to you neck ascender, loop runner, or ..... and remove it from the rope to make an adjustment, pass a limb or ....... there was a device made with it in two and once it was realized that it didn’t allow it to stay attached to neck tether to the bin it went. The reason for the disposal of the clevis is prevents someone from attaching it MRS. Hope that helps clarify.
Also for those that’s weren’t there or didn’t notice the upper eccentric pin is now a bit more of a triangle to allow for a more consistent contact between the upper bollard and itself.