If I had to guess, the orange part is the older, original galaxy. The orange or reddish stars are older stars. Then it captured a dust cloud or a younger galaxy that got torn apart and has it's own orbital plane. The blue stars are much younger stars. I think the orbital planes will pull on each other and will eventually form a single plane, probably in between the two existing planes.
If an old galaxy can surround itself with young stars, then so can I. 👍 👴