> Correct ones would look the exact same.

Unlikely. Official lyrics (printed in CD inserts, for example) often have punctuation mistakes, or they have no punctuation at all.

Unofficial lyrics can have the same words while still differing in punctuation, line breaks, capitalization, or spelling (since most languages have multiple ways to spell the same word -- color/colour, for example).

All the tiny variations could easily create a distinct fingerprint for each source of lyrics.