I got a 1 champion permanent and 1 champion shard from 1 hextech mystery champion coin.

Why did i get something that i shouldn't have gotten. Im happy that I got it but I didn't know it was possible. Is there a slight chance to get a random champion shard or something? I have heard that you can get hextech chests and keys when you are lucky opening hextech chests. I'm asking because I have 14 more of them so I could get hopefully Zoe out of it. So is there a change to get a bonus champ shard for it?