You can't have a mix of normal and spider or normal and anything, because normal isn't actually a morph. It just means lacking any genetic mutation.
Spider and woma are also dominant genes. So a snake can't be both spider and woma either, for example.
Ah... With so many co-dominate genes I thought a lot of the normal ones would be co-dominate. Admittedly, I didn't think they were genetic mutations, I just thought they were like hair colors. Does that make sense?