set interfaces tunnel tun0 address '192.168.0.15/24'
set interfaces tunnel tun0 encapsulation 'gre'
set interfaces tunnel tun0 parameters ip key '10'
set interfaces tunnel tun0 remote '192.168.0.10'
set interfaces tunnel tun0 source-address '192.168.0.15'

set interfaces tunnel tun1 address '192.168.0.15/24'
set interfaces tunnel tun1 encapsulation 'gre'
set interfaces tunnel tun1 parameters ip key '10'
set interfaces tunnel tun1 remote '192.168.0.10'
set interfaces tunnel tun1 source-address '192.168.0.15'

Report time:      2023-03-08 10:22:27
Image version:    VyOS 1.4-rolling-202302150317
Release train:    current

Built by:         autobuild@vyos.net
Built on:         Wed 15 Feb 2023 03:17 UTC
Build UUID:       e62b2d4d-c09c-4dd6-a722-884b782e4d13
Build commit ID:  5207b6f510d677

Architecture:     x86_64
Boot via:         installed image
System type:      KVM guest

Hardware vendor:  QEMU
Hardware model:   Standard PC (i440FX + PIIX, 1996)
Hardware S/N:
Hardware UUID:    9db6248c-4e0e-412f-979c-d3d087331a7e

Traceback (most recent call last):
  File "/usr/libexec/vyos/conf_mode/interfaces-tunnel.py", line 216, in <module>
    verify(c)
  File "/usr/libexec/vyos/conf_mode/interfaces-tunnel.py", line 139, in verify
    f'is already used for tunnel "{tunnel_if}"!')
NameError: name 'tunnel_if' is not defined