Help Identify Brake Caliper, Got an odd one... Options

[McMark]

I began rebuilding my brake calipers today and I have an odd rear caliper. The odd one has:

1. Cad plating
2. Large adjustment screw (like the 914/6 rear caliper).
3. The same size piston as a 914/4 (so it's not a six caliper).
4. Dual bleeder screws
5. The piston adjusting mechanism is different.

The odd one definitely looks a lot newer so I'm guessing it's a rebuild from someone, but it's pretty different. Here, have some pictures.

This one shows the cad plating. The odd one is on the left. (IMG:style_emoticons/default/wink.gif)
(IMG:http://www.914world.com/members/markd/misc/brakes/1.jpg)

Here is another shot of the cad plating and the dual bleeder screws.
(IMG:http://www.914world.com/members/markd/misc/brakes/2.jpg)

Here is the back of the pistons. The odd one is on the left again. A normal one is on the right. Notice the adjuster screw size.
(IMG:http://www.914world.com/members/markd/misc/brakes/pistons.jpg)

Any ideas? Any concerns?