f897ee3f88
## Summary It turns out that it's not uncommon to end up with repeated packages in requirements files when running `pip-sync`, e.g., you might have `anyio==4.0.0` specified multiple times. This PR relaxes our assertions in the install plan to allow such repeated packages, as long as the requirement markers are exactly the same (i.e., they are truly duplicates). Closes https://github.com/astral-sh/uv/issues/1552.