Icons are not an indicator to see if they are different abilities. The only thing that counts is the abilityId. If that is different, they apply different effects.
Rapid Maneuver shows two icons because there are two different abilities at work. My guess is, one effect carries the speed buff and the other the snare immunity.
Skills that have effects with different durations are split like that for simplicities sake. Why have an internal separation for the effect durations with additional code if you can just put 2 effects with different lengths on the player?