Two computers fighting over IP

I recently built my GF her pc, using my old mb, cpu, and ram, and she replaced the storage and gpu so no old OS or anything. My new pc only has the same storage and gpu from the old setup. Whenever both computers are on at the same time they fight over IP and get kicked off the internet every 5 seconds to 3 minutes at most. The best information I can find on my end is both computers are throwing errors in the event viewer saying this "The IP address lease 10.0.0.6 for the Network Card with network address 0x74563CE483D1 has been denied by the DHCP server 10.0.0.1 (The DHCP Server sent a DHCPNACK message)." with the ip either being like a 6 or 7 on the end.