Set them both as static within their network controls.
Are the two units that are conflicting connecting through a hub? you mentioned “The only way we can get both on at the same time is to connect one unit to a router with auto IP” so that begs the question: what are they being wired into when they have the conflict?
Ramsey- Ya if they are connected to a switch in the same office and that switch is connected to one jack in that office make sure you have configured your main Switch in server room to allow give multiple IP’s and internet access from one Jack. This happens a lot with power over ethernet.