I've got an issue with Blender - I've got a tongue with a shapekey on it to stick it out. I'm trying to add it to my avatar but when I merge the meshes, all the shapekeys from the avatar cause the tongue to stick out (as if the stick-out-tongue shapekey from the tongue mesh is applying to every shape key on the avatar). I've even tried separating the tongue back onto its own mesh, removing all the shapekeys each way, re-merging and finding myself back in the same spot. 

I'm totally out of ideas. It seems like a bug but I don't know how to avoid it. Can I get some help?