For NM everything in /etc/network/interfaces are just connection configuration - which are not bound to a particular device ... unless the names match devices NMis supposed to manage. So NM will consider them for devices that don't have any other explicit configuration.
My suggestion would be to configure eth0 and eth1 in interfaces too and if you still want to use NM, try to use managed=true in /etc/NetworkManager/nm-system-settings.conf
For NM everything in /etc/network/ interfaces are just connection configuration - which are not bound to a particular device ... unless the names match devices NMis supposed to manage. So NM will consider them for devices that don't have any other explicit configuration.
My suggestion would be to configure eth0 and eth1 in interfaces too and if you still want to use NM, try to use managed=true in /etc/NetworkMan ager/nm- system- settings. conf