Sylas ult on CD with Kled ult still "available"

Was playing an ARAM just now, and I had (as Sylas) stolen Kled's ult. Previously, I had used it at point blank range to try to get the end effect of Kled's ulti, however I had immediately died. Based on the replay at 0.25 speed, it looks like it DID get used (I kind of doubt one Azir auto with just a Nashor's does that much damage to a Kled) Upon dying, ult went on cooldown, as expected. What was NOT expected, however, was for it to both have Kled's ult still stolen, but also still available for use. Given the 200% cooldown, it was quite a while before I was able to actually use it (still as Kled's ult), but when I pinged the ultimate, it showed it in chat as ready, instead of as still being on cooldown. Not really sure how this can be replicated with any reliability. To note, at the same time I died, the enemy Kled's Skaarl went away (he was at like 75% hp prior hence I'm pretty sure the ulti went off the first time).