IMHO,
Such tool, if maked, It will not be very useful because of too many matches in files.
Redundancy of results..
However, the very formulation of the problem is interesting.

See old tool for similar purpose, but it searches only for 'string' duplicates inside one specially prepared [text or bin] file:

-> Dup_Str <-

- This tool does not prints line numbers of duplicated strings, - it prints only its duplicated strings.
It maked Q&D quite a long time ago, but used sometimes without changes.
Originally this tool was made to find duplicates of lexemes in the dictionary..