Duplicate terms and role based names

Is there possibility to create two names for a menu that depends from user role. I would like to have same menu showing differently to users inside organisation and outside. I know of taxnomy role. If I duplicate whole menu structure, it works, but is is difficult to maintain.

Other problem is that I would like the same document to exists in tho branches in menu tree, without duplicating the taxonomy. Duplicate taxonomies are difficult to users, but sometimes one term may relate to several upper terms.

I do not have deep understanding about synonyms or related terms. Can this be accomplished with those?