It's not the same artist. C418 had a very good deal with Notch's Mojang, letting him keep rights. Microsoft demanded that he sign over the rights to further music as work for hire. He refused, as a result the newer music in Minecraft is made by other composers who signed on to that deal and try to make music fitting with C418's style.

It's not hard to get into the library of congress? It's purposely extremely easy. I forgot who it was, but there was one big right-wing talk show host that would end all of his segments by saying it's being added to the Library of Congress as if it's an exclusive accolade, and people rightfully called him out on his shit for how easy it is to do that