How can I prevent items from being duplicated? Javascript

I have this code that customizes a json, but returns duplicate items, which will be necessary, so that duplicate items are not returned

I think that with the value of nid you could prevent items from being duplicated
any solution

Is there any easy way to do this.

Please have a look

Thanks for the help

let result = {};

   for (let item of data) {
     for (let subItem of item.itemsSlider) {
       if (!result[subItem.language]) {
         result[subItem.language] = [];
       }
       result[subItem.language].push(subItem);
     }
   }
   return result

this is the json
DATA:

const data = [
 {
    "itemsSlider": [
      {
        "nid": "61626",
        "status": "1",
        "titleNode": "01Additional Suitcase - EN",
        "language": "en_US"
      },
      {
        "nid": "61234",
        "status": "1",
        "titleNode": "01Additional Suitcase - EN",
        "language": "en_US"
      }
    ]
  },
  {
    "nid": "61567",
    "title": "K02 - Kiosk Slider - EN",
    "itemsSlider": [
      {
        "nid": "616098",
        "status": "1",
        "titleNode": "01Additional Suitcase - EN",
        "language": "es_MX"
      },
      {
        "nid": "616321",
        "status": "1",
        "titleNode": "01Additional Suitcase - EN",
        "language": "es_MX"
      }
    ]
  },
  {
    "nid": "61629",
    "title": "K02 - Kiosk Slider - EN",
    "itemsSlider": [
      {
        "nid": "616347",
        "status": "1",
        "titleNode": "01Additional Suitcase - EN",
        "language": "fr_FR"
      },
      {
        "nid": "61555",
        "status": "1",
        "titleNode": "01Additional Suitcase - EN",
        "language": "fr_FR"
      }
    ]
  },
  {
    "nid": "61629",
    "title": "K02 - Kiosk Slider - Mix",
    "itemsSlider": [
      {
        "nid": "616567",
        "status": "1",
        "titleNode": "01Additional Suitcase - EN",
        "language": "es_MX"
      },
      {
        "nid": "61626",
        "status": "1",
        "titleNode": "01Additional Suitcase - EN",
        "language": "en_US"
      }
    ]
  }
]