No actually I think you're right - it does appear to be broken. I'll have to reexamine my own and post a better pic of the back.
It seems as if they both broke the same way, which would make sense because the design on the front is exactly the same (how cool is that).
No I never heard of a "bent-on" version before either but then again I never heard of a shoe button cover until this week. Pretty cool.
here is the back of one shoe button, looks exactly like the back of mine.http://www.buttoncountry.com/Div4Images/3-Covers/b39-RealButterflyPaint-1716-Bf.jpg