OCT titles

I was just entering my copy of Denys Page's Aeschylus OCT into Librarything when I noticed that one library gave the title as 'Aeschyli Septem Quae Supersunt Tragoedias [SIC].'

The jacket, the title page, and the OUP website use the accusative 'Tragoedias,' but why? The spine reads simply Aeschyli Tragoediae.

In full 'Aeschyli Septem Quae Supersunt Tragoedias edidit Denys Page' sounds like an excited statement:

'Denys Page has published the seven surviving tragedies of Aeschylus!' Oh my god! I can't even believe it!

I'm inclined to think this is actually what was intended (though I exaggerate). One could make the argument that those editions which display 'Fabulae' or 'Tragoediae' on their title pages are mistaken. What, then, would 'edidit,' 'recensuit,' or 'adnotatione instruxit' govern? One would have to read something like '... Fabulae (sc. quas) edidit ....'

Titles that use ambiguous words are plentiful, 'Opera' being the most obvious. But what about 'Carmina,' 'Historica,' 'Lyrica,' or even 'Delectus'?

Or maybe OUP just made a mistake.