Pass in an entire yarn.lock file contents and this will spit out duplicate resolutions

get-yarn-lock-dupes.js

function getYarnLockDupes(yarnLock) {
  return yarnLock
    .split('\n')
    .filter(a => !a.startsWith(' ') && !a.startsWith('#'))
    .map(a => a.replace(/[:"]/g, ''))
    .flatMap(a => a.split(/, ?/g))
    .filter(a => a)
    .flatMap(a => {
      const versions = a.split(' || ');
      if (versions.length === 1) { return a; }
      const name = versions[0].split('@');
      versions[0] = versions[0].split('@')[1];
      return versions.map(b => `${name}@${b}`);
    })
    .map(a => a.replace(/^@/g, '™'))
    .map(a => a.split('@').map(a => a.replace(/™/g, '@')))
    .filter((a, i, arr) =>
      (arr.filter(([b]) => a[0] === b)).length > 1
    )
    .sort(([a], [b]) => a.localeCompare(b))
    .reduce((acc, [name, version]) => {
      acc[name] || (acc[name] = []);
      acc[name].push(version);
      acc[name] = acc[name].filter((a, i, arr) => arr.indexOf(a) === i);
      return acc;
    }, {});
}