Papers can't lie? Wrong, just the same (9)
I believe the answer is:
identical
'just the same' is the definition.
(I've seen this before)
'papers can't lie? wrong' is the wordplay.
'papers' becomes 'ID' (identification papers).
'wrong' indicates anagramming the letters.
'cant'+'lie'='cantlie'
'cantlie' is an anagram of 'entical'.
'id'+'entical'='IDENTICAL'
(Other definitions for identical that I've seen before include "Equal" , "not distinguished" , "Similar" , "Matching" , "Impossible to tell apart" .)