Exception: "An item with the same key has already been added" while comparing commits

Reproduction steps

repository.Diff.Compare<Patch>(commitB.Tree, commitA.Tree);

Expected behavior

patch

Actual behavior

"exception": "System.ArgumentException: An item with the same key has already been added. Key: tools/firmware-utils/src/bcm_tag.h\n at System.Collections.Generic.Dictionary`2.TryInsert(TKey key, TValue value, InsertionBehavior behavior)\n at System.Collections.Generic.Dictionary`2.Add(TKey key, TValue value)\n at LibGit2Sharp.Patch..ctor(DiffHandle diff)\n at LibGit2Sharp.Diff.u003cu003ec.u003c.cctoru003eb__36_0(DiffHandle diff)\n at LibGit2Sharp.Diff.BuildDiffResult[T](DiffHandle diff)\n at LibGit2Sharp.Diff.Compare[T](Tree oldTree, Tree newTree, IEnumerable`1 paths, ExplicitPathsOptions explicitPathsOptions, CompareOptions compareOptions)\n at

Version of LibGit2Sharp (release number or SHA1)

libgit2sharp/0.26.2

Operating system(s) tested; .NET runtime tested

ubuntu docker mcr.microsoft.com/dotnet/core/aspnet:3.1-bionic

Start by reproducing repository.Diff.Compare< Patch >(commitB.Tree, commitA.Tree) with the reported commits and review the stack trace through Diff.Compare and LibGit2Sharp.Patch. Inspect how the duplicate path tools/firmware-utils/src/bcm_tag.h is handled; done means the comparison returns a patch instead of throwing the duplicate-key exception.