Hexteck Reroll bugged

So, i've got 3 champion shards before and i rerolled them and i got Twisted Fate shard, a champion which i own... And fiy, i don't have all the champions, maybe around half of them, so why didn't i get a permanent champion from the reroll?

"Reroll three similar types of loot into permanent loot of the same type (for example, reroll three different champion shards into a permanent champion guaranteed not to be a duplicate of one you own). "

Also, i've opened a 4th chest before and got a Twisted Fate shard there too (yes, not 3 shards reroll this time, just chest, just to make it clear), is that just random or is it some kind of ''Twisted Fate shard'' bug? :S