Versione corretta del file /etc/network/interfaces
# Loopback interface
auto lo
iface lo inet loopback
# Interfaccia principale enp1s0
auto enp1s0
iface enp1s0 inet static
address 192.168.1.51
netmask 255.255.255.0
gateway 192.168.1.254
dns-nameservers 1.1.1.1 8.8.8.8
# Seconda interfaccia enp2s0
auto enp2s0
iface enp2s0 inet static
address 192.168.1.52
netmask 255.255.255.0
dns-nameservers 1.1.1.1 8.8.8.8