I've noticed that with different words the words double, two, and duo work differently. Why so and how different are they? Are they interchangeable?
- A double-barrel shotgun (why not a two-barrel or duo-barrel)
- A duo-core processor (why not a double-core or a two-core)
- A two-headed giant (why not a double-headed or a duo-headed)
Sometimes I also see the words pair and dual used in the same way.
- A pair-legged creature.
- A dual-color gradient.