multiple inputs are not merged in output

When providing two packages as argument the output contains one package twice if it's in the rebuild or over the other package for example:

[jelle@natrium][~/projects/arch-rebuild-order]%cargo run blender opencolorio
    Finished dev [unoptimized + debuginfo] target(s) in 0.02s
     Running `target/debug/arch-rebuild-order blender opencolorio`
opencolorio krita krita-plugin-gmic openimageio openshadinglanguage blender blender