Why doesn't Chrome allow changing animation settings without duplicating keyframes?

Question

css

On the project, I encountered an interesting bug in Chrome (37.0.2062.124 m).
If we set the animation for an element to :hover and the state class is .is-loading , with different settings ( duration and iteration-count ), then the browser doesn't allow the same keyframes to be used.
Example .
Maybe there is a better way to solve this problem than to duplicate the animation?
Ps In Firefox, everything is fine with a single definition of keyframes.