skin shard question

i crafted this legacy skin shard tempest janna so i have it as permenant , but , when i did that i found that it was added as a permenant skin shard in the loot . so when i clicked on it there were options as to - unlock it as permenant / reroll into a random permenant skin / ( disenchant or something else )

usually it instantly unlocks the skin permenantly for me , but why did it have this unusual extra step where i can choose to do something else , can i reroll this single skin "alone" into another permenant skin shard ? meaning it would be alot better if i reroll in this way instead of rerolling 3 skin shards wasting alot more worth-of-essence .