"by the by" meaning in Anglais

{
  "categories": [
    {
      "kind": "other",
      "name": "Locutions adverbiales en anglais",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Anglais",
      "orig": "anglais",
      "parents": [],
      "source": "w"
    }
  ],
  "forms": [
    {
      "form": "by the bye"
    }
  ],
  "lang": "Anglais",
  "lang_code": "en",
  "pos": "adv",
  "pos_title": "Locution adverbiale",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Exemples en anglais",
          "parents": [],
          "source": "w"
        }
      ],
      "examples": [
        {
          "bold_text_offsets": [
            [
              25,
              34
            ]
          ],
          "ref": "Nathaniel Hawthorne, The Scarlet Letter",
          "text": "The old Inspector — who, by the by, I regret to say, was overthrown and killed by a horse, some time ago; […]",
          "translation": "Le vieil inspecteur — qui, à propos, ai-je le regret de dire, fut renversé et tué par un cheval, il y a quelque temps ; […]"
        }
      ],
      "glosses": [
        "Au fait, à propos."
      ],
      "id": "fr-by_the_by-en-adv-ihl-PUkJ"
    }
  ],
  "sounds": [
    {
      "ipa": "\\ˈbaɪ ðə ˈbaɪ\\"
    }
  ],
  "synonyms": [
    {
      "word": "by the way"
    }
  ],
  "word": "by the by"
}

{
  "categories": [
    "Locutions adverbiales en anglais",
    "anglais"
  ],
  "forms": [
    {
      "form": "by the bye"
    }
  ],
  "lang": "Anglais",
  "lang_code": "en",
  "pos": "adv",
  "pos_title": "Locution adverbiale",
  "senses": [
    {
      "categories": [
        "Exemples en anglais"
      ],
      "examples": [
        {
          "bold_text_offsets": [
            [
              25,
              34
            ]
          ],
          "ref": "Nathaniel Hawthorne, The Scarlet Letter",
          "text": "The old Inspector — who, by the by, I regret to say, was overthrown and killed by a horse, some time ago; […]",
          "translation": "Le vieil inspecteur — qui, à propos, ai-je le regret de dire, fut renversé et tué par un cheval, il y a quelque temps ; […]"
        }
      ],
      "glosses": [
        "Au fait, à propos."
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "\\ˈbaɪ ðə ˈbaɪ\\"
    }
  ],
  "synonyms": [
    {
      "word": "by the way"
    }
  ],
  "word": "by the by"
}