PvZ2 or Garden Warfare?
I'll assume Garden Warfare.
Yes you can run as many copies as you own from the same IP. You might need to play with your router settings (i.e. uPnP).
Yes you need multiple copies as only 1 Origin account can be active at a time.
We have no problem playing multiple copies together. My house is wired up closer to a small business instead of a normal house though in terms of equipment.
