Helixa Hyslop was one of the discoverers of the Doubling Charm. She and her twin sister, Syna Hyslop, discovered the Doubling Charm together, and used it to duplicate every object in their mansion (BoS).
Helixa had a twin sister named Syna (BoS).
Performing the Doubling Charm
Helixa: As in a DNA double helix