There is a recipe for a magenta dye that looks like
4x (magenta dye) = (blue dye) + 2x (red dye) + (white dye)
Also one of the recipes for light blue dye looks like
2x (lighblue dye) = (blue dye) + (white dye)
Therefore it seems natural to have a recipe
2x (magenta dye) = (lightblue dye) + (red dye)
This may make it easier when you are starting in a swamp biome. You have easy access to blue orchids, and poppies can be found in pretty much every biome.
Also seems similar to
MC-75303