Sorry, the subnet of pc1 is 255.255.255.0
The subnets aren’t the most important part. You need to use different IP ranges on the NICs.
Assuming that nic1 on PC1 is a public IP address, you need to use a private IP range on the other NIC such as 10.0.0.2 (and 10.0.0.3 for PC2) with a subnet of 255.255.255.0. If the IP that you get when you VPN into the other company is in that IP range then you’ll need to pick a different one like 192.168.0.2 and 192.168.0.3.
My only questions is: why is the Public WAN IP going straight from the ISP to the PC? I recommend setting some sort of multi-port router (get a good one at best-buy for $60) and put the Public IP on the router.
Then, like everyones saying, make sure your internal IP range is unique from the remote VPN LAN, configure PC 2 w/o a gateway IP , etc etc…