Diferença entre rc.local.service e rc-local.service

Diferença entre rc.local.service e rc-local.service

Eu tenho um link simbólico ativado

/lib/systemd/system/rc.local.service -> rc-local.service

Eu obtenho resultados diferentes usando

systemctl status rc.local.service
● rc.local.service - /etc/rc.local Compatibility
   Loaded: loaded (/etc/systemd/system/rc.local.service; disabled; vendor preset: enabled)
   Active: inactive (dead)

e

systemctl status rc-local.service
● rc-local.service - /etc/rc.local Compatibility
   Loaded: loaded (/etc/systemd/system/rc-local.service; enabled; vendor preset: enabled)
  Drop-In: /lib/systemd/system/rc-local.service.d
           └─debian.conf
   Active: active (exited) since Do 2016-04-21 09:12:58 CEST; 1h 1min ago
  Process: 1503 ExecStart=/etc/rc.local start (code=exited, status=0/SUCCESS)

Apr 21 09:12:58 ubuntu systemd[1]: Starting /etc/rc.local Compatibility...
Apr 21 09:12:58 ubuntu systemd[1]: Started /etc/rc.local Compatibility.

Esta é a configuração correta? E qual é a diferença em chamar o serviço de link simbólico?

O arquivo /etc/rc.local não seria executado duas vezes dessa maneira?

(Testado no Ubuntu 15.10 e 16.04)


EDITAR:

ls -lahi /etc/systemd/system/rc* /lib/systemd/system/rc*local.service 
1980102 -rw-r--r-- 1 root root 650 Nov 10  2015 /etc/systemd/system/rc-local.service
1980094 -rw-r--r-- 1 root root 650 Nov 10  2015 /etc/systemd/system/rc.local.service
2891510 -rw-r--r-- 1 root root 612 Sep  7 11:32 /lib/systemd/system/rc-local.service
2906434 lrwxrwxrwx 1 root root  16 Sep  7 11:33 /lib/systemd/system/rc.local.service -> rc-local.service

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