εἰ δὲ ὧν μὲν μάλιστα ἄνθρωποι ἐπιθυμοῦσιν ὁ δαίμων ἡμῖν ταῦτα συμπαρεσκεύακεν, ὡς δ᾽ ἂν ἥδιστα ταῦτα φαίνοιτο αὐτός τις αὑτῷ ταῦτα παρασκευάσει,
if the deity has assisted us in getting what most men desire, one will so arrange these things with respect to himself, that they should appear the most pleasant.
Miller: Now if God has helped us to obtain that which men most desire, and if any one will so order these results for himself that they shall give as great pleasure as possible,
Where does he get the second if from?
Presumably it’s because of the μὲν… δὲ.
Smyth 2904 b says
εἰ, οὐ (μή) standing before μὲν . . . δέ exercise their force on both opposed clauses.
So we’d have two protasis clauses and the apodosis would come after the section you’ve quoted, i.e. …ὁ τοιοῦτος ἀνὴρ τοσούτῳ πλεονεκτήσει etc
I think the meaning is this: the daimon helped us to get what most people want, but one himself, i,e, not the daimon, will, to make the things appear most pleasant, arrange etc.