Multi-Ult Lux Bug

So I played a game yesterday, and I encountered a Lux who used the Hextech Protobelt with her ult to create multiple copies of her ult. The odd thing is is that each copy made is an illusion (doesn't deal damage or apply on hit effects) except the last copy.I assumed this was a glitch, but it's possible that the person playing Lux may have been cheating. I do not own Lux, so testing this bug isn't possible for me right now. Has anyone else encountered this? Note, this is the first time I made a post, so I'm not sure if the link I attached will show up or not, so here's another copy: https://youtu.be/84EDSjNClpI