A cargo subcommand for displaying when different versions of a same dependency are pulled in.
Once installed, running cargo duplicates in a project directory looks like the following:
```text $ cargo duplicates Package Versions ------- -------- cfg-if 1.0.0 0.1.10 hex 0.4.2 0.3.2 humantime 2.0.1 1.3.0
cfg-if 1.0.0: - Because of cargo 0.48.0 => flate2 1.0.19 => crc32fast 1.2.1 => cfg-if 1.0.0 cfg-if 0.1.10: - Because of cargo 0.48.0 => crossbeam-utils 0.7.2 => cfg-if 0.1.10
hex 0.4.2: - Because of cargo 0.48.0 => hex 0.4.2 hex 0.3.2: - Because of cargo 0.48.0 => crypto-hash 0.3.4 => hex 0.3.2
humantime 2.0.1: - Because of cargo 0.48.0 => humantime 2.0.1 humantime 1.3.0: - Because of cargo 0.48.0 => env_logger 0.7.1 => humantime 1.3.0 ```