Double Comparison.—Two adjectives (or adverbs) referring to the same subject, when compared with each other, are both put in the comparative; ἤ is always used:
ἡ εἰρήνη ἀναγκαιοτέρα_ ἢ καλλί_ων
συντομώτερον ἢ σαφέστερον διαλεχθῆναι
a. μᾶλλον may be used with the first adjective in the positive (cp. cross1065), and ἤ before the second:
πρόθυ_μος μᾶλλον ἢ σοφωτέρα_
Herbert Weir Smyth [n.d.], A Greek Grammar for Colleges; Machine readable text [info] [word count] [Smyth].