If someone wants to purchase a Dover score, which is PD worldwide, scan and post it, I'll be happy to tag it V/V/V so it can be downloaded as much as you like.
It's the publisher, yes. If it's public domain, then most likely it's the unrevised version, probably with some different tempo markings, articulation, etc.
Dover is primarily a reprint publisher (though they do issue a couple of new editions that are under copyright). They reprint works that are public domain and offer them at a very reasonable price. Their reprint quality is often very good, though (like everyone) they mess up now and again. Reprinting the Soviet edition of Tchaikovsky's 1812 Overture (where the editors had to replace the quotation of the old Russian national anthem because of the government) is a case where they really dropped the ball.
There are other reprint publishers - namely Kalmus and Lucks. Other publishers who aren't normally known as reprint houses have been known to reprint public domain items as well (Schirmer, Boosey and Hawkes).
( not the original version )who can explain me what a dover score is?