We don't have synonyms for self-same yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are selfsame, self-made and self same.
(adj) :
Alternative form of selfsame. [Chiefly preceded by the: precisely the same; the very same; the same not only in being similar but in being identical.]
(n) :
Alternative form of selfsame. [(archaic) Chiefly preceded by the: precisely the same person or thing.]
(adj) :
Alternative form of selfsame. [Chiefly preceded by the: precisely the same; the very same; the same not only in being similar but in being identical.]
(n) :
Alternative form of selfsame. [(archaic) Chiefly preceded by the: precisely the same person or thing.]