After the nylon line, the next point of weakness in retracting badge holders are the vinyl straps. They either tend to rip due to cold weather and UV exposure, break due to hanging two or more badges, or the snap-fasteners become deformed.
This thing is used to replace that strap. It can hold two badges, and can fit most of the split-rings that are on most retractable badge holders.
I'll try to update the Badge Ring so that it will snap into place and not slide off the holder too easily.

Update: Sorry I haven't uploaded a rotated version of the strap replacement, but like most others, I've been busy! However I have a hint... for those that are saavy with OpenSCAD, you can create a "Badge Ring" that is nice and long... I was initially trying to figure out a detente system in which the ring won't slip off the badge holder, but if the ring is "tall" enough, it should keep itself positioned between your badges and the retracting reel. When you need to replace the badge, you just pull the badges until enough wire is expose to the slide the ring up so that the badges can slip out.

This item should print sideways. You may want to rotate it 90 degrees on the Y-axis before slicing.
To install:
1: Find the small split ring at the end of your retractable badge holder.
2: Pry it open with two pliers and remove the old vinyl strap.
3: Replace the strap with the Thing.
4: Re-install the split ring on the retractable badge holder.
5: Slide the Badge Ring up to the split ring.
6: Pull one of the flat planks away from the body. It should hinge outward.
7: Thread that plank through the hole where the vinyl strap used to go for your badge.
8: Repeat with your second badge (on the other plank) if necessary.
9: Slide down the Badge Ring to keep the planks closed.