Ekko Double Stun Intended Mechanic?

I think this was probably around since 6.22 when Ekko's R was made to proc. the W.

This leads to a cool mechanic where if you stun someone with W and then R just as W is about to fade, you can double stun. It almost never happens but it's satisfying to pull off.

If it's a bug, I don't want to use it but if it's some really situational mechanic I'd love to try to think about how I can make it work sometimes. I'd just like official confirmation one way or the other. I've never been able to do it in-game but here's video demonstration: https://www.youtube.com/watch?v=uefvGLOCXso