const fs = require("fs")
const filename = "index.js".split(".") //filename like 0.gif to gif
const times = 10 // number of times to duplicate

for(var int = 1; int < times; int++){
    const newFilename = `${(parseInt(filename[0]) + init)}.${filename[1]}`  //new filename like 0.gif to 1.gif
    fs.copyFileSync(filename, newfilename)
}

use the write file and read file from the fs module and a simple for loop

The simplest option is to use fs and using copyFile function available

const fs = require("fs");
const path = require("path");

let copyMultiple = (src, count) => {
 let initCount = 0;

 while (initCount < count) {
   initCount++;// you can put this at bottom too acc to your needs
   const newFileName = `${initCount}_${initCount}${path.extname(src)}`;
   console.log(newFileName, "is new file name");
   fs.copyFile(src, newFileName, (error) => {
     // if errors comes
     if (error) {
       console.log(error);
     }
   });
 }
};
copyMultiple("1.gif", 3);

Another elegant way of doing this is

const util = require("util");
const fs = require("fs");
const path = require("path");
const copyFilePromise = util.promisify(fs.copyFile);

function copyFiles(srcFile, destDir, destFileNames) {
  return Promise.all(
    destFileNames.map((file) => {
      return copyFilePromise(srcFile, path.join(destDir, file));
    })
  );
}

const myDestinationFileNames = ["second.gif", "third.gif"];
const sourceFileName = "1.gif";

copyFiles(sourceFileName, "", myDestinationFileNames)
  .then(() => {
    console.log("Copying is Done");
  })
  .catch((err) => {
    console.log("Got and Error", error);
  });

Using this will also give upperhand of knowing when it is done.

You can read docs here

not sure which framework you're on but fs.copyFile() is the standard way for node.js https://nodejs.org/api/fs.html#fscopyfilesrc-dest-mode-callback