Can remote users on the VPN be accessible from the same IP address as when they are physically on the network?

If you want to use same ip address on same network, you have to bridge vpn network and physicial network.

If you are use OpenVPN, you have to use tap device for Layer2 communication.
Disable DHCP configuration in OpenVPN.
Bridge OpenVPN interface (such as tap0) to your interface which is connected to company network.
Now each client see physical network and VPN network at same time. But ip address might different due to different mac on Wi-Fi card and OpenVPN tap device.
You can set IP address to device via DHCP settings on router or server.
If you get a conflict err on DHCP server, you can represent same mac address which is Wi-Fi to vpn tap device or enter static IP to tap device on computer.