Board Thread:Producer, illustrator,& music discussion/@comment-58.71.224.84-20170714023812/@comment-53539-20170714100323

Kagamine means "Mirror sound" actually.

They are designed to be androids like Miku was originally and Luka was the same, though all original intentions have since been dropped. Their part of the "Character Vocal Series" which feature singers based on sound, Miku is sound when its first spoken, the Kagamines represent sound reflecting (an echo) and Luka after its traveled (hence why she had English originally).

Since they are essentially as Wat puts it "one soul to two bodies" they share the same "surname" but its not a indication they are siblings. It just means they are twins, as in, they are a pair. Think of them like a matching set of salt and pepper shakers rather then twins.