Is it rare for two different anime to share the same OP/ED song?


I have watched the anime _[Ano Hi Mita Hana no Namae wo Bokutachi wa Mada
Shiranai](https://myanimelist.net/anime/9989/Ano_Hi_Mita_Hana_no_Namae_wo_Bokutachi_wa_Mada_Shiranai)._
It has the ED song

> "secret base ~Kimi ga Kureta Mono~ (10 years after ver.) (secret base
> 〜君がくれたもの〜（10 years after Ver.）)" by Meiko Honma (Ai Kayano), Naruko Anjou
> (Haruka Tomatsu), Chiriko Tsurumi (Saori Hayami)

A few years later after I watched AnoHana, I watched an old anime, _[Kyou no 5
no 2](https://myanimelist.net/anime/4903/Kyou_no_5_no_2_TV)_. I heard one of
its ED songs, and it's really similar to AnoHana's ED song. The title of Kyou
no 5 no 2's ED song was like:

> "secret base ~Kimi ga Kureta Mono~ 「secret base ～君がくれたもの～」" by Friends: Yuu
> Kobayashi, Asami Shimoda, MAKO, Satomi Akesaka, Youko Honda, Kana Asumi

So my question: **Is it possible/rare for a song that is used in the OP/ED of
an anime to be used also in the OP/ED of a different anime?**

Has this ever happened to other anime? Or is it just a coincidence?




Very rare.

The only instance I can think of is _Elfen Lied_ (2004) and _Otogizoushi_
(2004).  
And it's very indirect.

Both of them share the same ED Single CD which has these tracks:

  1. Be your girl
  2. Hoshi ni negai wo
  3. Be your girl (karaoke)
  4. Hoshi ni negai wo (karaoke)

"Be your girl" is the ED of _Elfen Lied_ , while "Hoshi ni negai wo" is the ED
of _Otogizoushi_.




Very rare.

The only instance I can think of is _Elfen Lied_ (2004) and _Otogizoushi_
(2004).  
And it's very indirect.

Both of them share the same ED Single CD which has these tracks:

  1. Be your girl
  2. Hoshi ni negai wo
  3. Be your girl (karaoke)
  4. Hoshi ni negai wo (karaoke)

"Be your girl" is the ED of _Elfen Lied_ , while "Hoshi ni negai wo" is the ED
of _Otogizoushi_.

