Yes, it is possible to separate the head and body into two different Spine files and combine them at runtime. This approach allows you to maintain and update the head and body animations independently, making it easier to manage different body types or poses without needing to recreate or import the head for each variation. You can animate them together in Spine or your game engine, depending on your workflow and the capabilities of the game engine you are using.

For instance, as mentioned in the forum discussions, you can animate multiple skeletons together in a single Spine file and then export the animations via JSON to import them into separate characters. Alternatively, some game engines, like Unity with the spine-unity runtime, support combining skeletons at runtime. This means you could have a separate skeleton for the head and another for the body, and then programmatically position and animate them together in your game.

However, it's important to note that managing separate skeletons for the head and body might require additional considerations, such as ensuring consistent animation timing and handling the attachment points between the head and body. Some users have successfully used this approach by drawing the head on top of the body at runtime, effectively combining them without needing extra bones for attachment.

Using separate skeletons for the head and body can work. For example, Delver's Drop does that:

In that case I suggest creating both skeletons in the same project, so you can see the animations together.

Any time your workflow involves creating a copy of everything, you probably want to stop and find a better way!

You will likely find it easier to use a single skeleton. That also gives you more flexibility, as you can change the draw order in animations so the head is on top of behind parts of the body.