A python library with C/fortran is different than a C-only library. eigen is a great example of this. Many python packages depend on eigen, and there even exist

A python library with C/fortran is different than a C-only library. eigen is a great example of this. Many python packages depend on eigen, and there even exists a pyeigen, but assuredly almost none of them depend on pyeigen. In conda, you can declare this properly, and you can have one true eigen in your environment.