I don't see that just because the planet has a name it necessarily had to have people living on it before the Shards arrived. Look at our solar system, 8 (9) planets all with names, but only one has life. Stars, planets, solar systems all have names throughout our universe even though we've never even been remotely close to investigating them ourselves.
Maybe wherever the Shardholders came from was a somewhat advanced culture like ours with telescopes and such, and so named some of the planets they could see as we do.