Allow two pages in separate folders to have same file name

Currently, there is a bug, when we have to files with the same file name (but in different folders), one of them will not appear in the menu. (e.g. pages/projects/buildworkshops.mdx and pages/fchh/buildworkshops.mdx).

Investigate why this happens, and if we can fix it, or if this is just a limitation we have to live with. Probably something in the menu building algorithm.