How to add multiple ipv4-to-ipv6 tunnels?

Question

linux

Adding the first tunnel

ip tunnel add ipv6tunnel mode sit remote 209.51.161.17 local 45.139.184.125 ttl 255
ip link set ipv6tunnel up
ip addr add 2001:470:1f06:2f8::2/64 dev ipv6tunnel
ip route add ::/0 dev ipv6tunnel

Problem when I add the second one

ip tunnel add ipv6tunnel-2 mode sit remote 184.105.250.77 local 185.230.132.140 ttl 255
ip link set ipv6tunnel-2 up
ip addr add 2001:470:39:1da::2/64 dev ipv6tunnel-2

And when I add a route, I get an error
ip route add ::/0 dev ipv6tunnel-2
RTNETLINK answers: File exists
How to add several ipv4-to-ipv6 tunnels correctly?

route -nA inet6

[email protected]:~# route -nA inet6
Kernel IPv6 routing table
Destination                    Next Hop                   Flag Met Ref Use If
::1/128                        ::                         U    256 1     0 lo
2001:470:39:1da::/64           ::                         Un   256 1     0 ipv6tunnel-2
2001:470:1f06:2f8::/64         ::                         Un   256 1     0 ipv6tunnel
fe80::/64                      ::                         U    256 1     0 eth0
fe80::/64                      ::                         Un   256 1     0 ipv6tunnel
fe80::/64                      ::                         Un   256 1     0 ipv6tunnel-2
::/0                           ::                         U    1024 2    75 ipv6tunnel
::1/128                        ::                         Un   0   3    11 lo
2001:470:39:1da::2/128         ::                         Un   0   2     0 ipv6tunnel-2
2001:470:1f06:2f8::2/128       ::                         Un   0   3    75 ipv6tunnel
fe80::2d8b:b87d/128            ::                         Un   0   2     0 ipv6tunnel
fe80::b9e6:848c/128            ::                         Un   0   2     0 ipv6tunnel-2
fe80::5054:ff:fe51:e932/128    ::                         Un   0   2     0 eth0
ff00::/8                       ::                         U    256 2     8 eth0
ff00::/8                       ::                         U    256 1     0 ipv6tunnel
ff00::/8                       ::                         U    256 1     0 ipv6tunnel-2
::/0                           ::                         !n   -1  1     1 lo

Answer 1

He most likely swears at the existence of a default route with the same metric as you are trying to add. Routes added via ip route do not inherit interface metrics.