Gameplay Bug? Redemption Interaction with Ornn

I was just playing a game and I purchased redemption. During a heated teamfight I cast redemption, and died shortly thereafter, beginning the cooldown on redemption and my respawn timer. So far so good. Then as I was shopping during my death, I decided to buy salvation upgrade to redemption, as an ornn was on my team. When I did this, my redemption's cooldown was 1min40sec. Then after purchasing salvation, the cd changed to 15 sec, which was my death timer. Upon respawning I found that redemption, or rather salvation was ready to use, JUST 15 seconds after using it. Im not sure if this is a bug or just an oversight regarding the new upgrade system but It seems rather busted in the wrong hands essentially getting access to 2 back to back redemptions. 15 seconds seems like a short enough time to effectively get 2 in one teamfight!