Multiple calls to AddPropertiesToElement fail

[MikeJPelton]

A second call to AddPropertiesToElement raises the "already exist property key vertex" exception.

using (var writeStream = new FileStream(outputFilePath, FileMode.Create, FileAccess.Write))
            {
                PlyFile writeFile = new() { IsBinary = true };
                writeFile.AddPropertiesToElement("vertex", new[] { "x", "y", "z" }, xyz);
                writeFile.AddPropertiesToElement("vertex", new[] { "nx", "ny", "nz" }, normals);
                writeFile.AddPropertiesToElement("vertex", new[] { "red", "green", "blue" }, rgb);
                writeFile.Write(writeStream);
            }

...fails on the second call, but the original C++ code examples do exactly this. The only to add data of multiple types (floats for position and bytes for colour for example) is to make multiple calls. Your code tries to create the vertex element a second time and fails, instead it should reference the existing element. I am cobbling a workaround together which I will share if it succeeds.