`rescript build` panics when two modules have the same name

[mvaled]

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• Is it a bug? Usage questions should often be asked in the forum instead.
• Concise, focused, friendly issue title & description.
• A minimal, reproducible example.
• OS and browser versions, if relevant.
• Is it already fixed in master? Instructions

Summary

I created by accident a copy of the file and rescript build went in to panic

This is enough to reproduce:

$ tree src 
src
├── a
│   └── Test.res
└── b
    └── Test.res

note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
error Command failed with exit code 101.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.