UV2 blown out when calling ToMesh()

I am building a mesh via scripts:

Code (CSharp):

1. var importer = new pb_MeshImporter(pb);
2.             var settings = pb_MeshImporter.Settings.Default;
3.            
4.             settings.quads = false;
5.             importer.Import(mesh, mats, settings);
6.             //pb.ToMesh(MeshTopology.Quads);

If I uncomment the last line then UV2 will get blown out and will be a copy of UV. I am uncertain what that line does in hindsight so maybe this is intentional behavior? I must have gotten it from an example and thought it was necessary to build the pb_object.

It seems like a bug to me but I wasn't certain so I thought I'd post here first and see if anyone had insight on what that function does and whether or not it should be wiping out the UV2s.