I generally have a problem with assuming that a filename is similar to another. I don't know your specific context here so I might be wrong. 
The idea is that for ogs6 not all files need to have the same name, we want to be able to load multiple geometries, meshes, etc. and if you assume that a certain filename matches another this *might* result in problems later. Again, I don't know your're context here. I am just saying that you should keep this in mind and maybe it makes sense to give two filenames here, one for each of the files.