This small utility can check yarn.lock file for having same versions of one package.

Example:

For check yarn.lock file - yarn check-duplicates -s @babel -t yarn For check package-lock.json file - yarn check-duplicates -s @babel -t package

If yarn.lock file has more than one version of any babel package, you'll receive exitCode=1 and see something like this:

Packages installed from scope @babel has duplicates:
...

If there isn't problems with package versions, you'll see

Packages installed from scope @babel has no duplicates.
...