Rogue Flow Confusion

The flow passive says using a unique skill grants you a stack of flow. However, while having a point in the flow passive I noticed that skills with multiple animations give you multiple stacks of flow. For example: cinder strike has 3 different animations, giving you 3 stacks of flow. Is this intentional or a bug?

Kinda, each hit in Cinderstrike and Dancing Strikes are both coded as unique skills so they all count for Flow.