I have an idea, it might not actually work, or anything, but here goes:
I'm not sure, but while the model limit has been reached, but the skin limit hasn't. if this is so (again, don't quote me), then we could reuse the model for the C. Evocata, but use different skins for C. Praetoriana and C. Imperitoria. likewise, we could use a different skin for E. Praetoriana for another Roman horse unit.

Just my 2 cent...