Sure, I got you there, and am happy to accept the difference in voices (and am not, as one whose understanding of Biblical Greek is at the level of an acquaintance, not any deep and intense study, sure of what to make of that difference in voices) as a reason at least to think about a difference in active/passive acts of God. This passive/active voice distinction has many uses, doesn't it? Certainly it doesn't connote a difference in intentionality?
This verse needs to be read in context of 9:21, though - as Ken pointed out - some are made for honorable use, and some for dishonorable... are the verbs there active and passive, respectively, also? It would certainly strengthen the case for a strict difference if that were so.
My main point in the discussion is not to make an argument for double predestination, per se - but to uphold God's active intentionality with respect to the destinations of all people, elect and non-elect alike. I find that most of the time when there is being made a strict active/passive distinction, (and i know you guys aren't doing this) what is being said is that God didn't exercise his will to send people to hell... that it's against his wishes, but he, being the gentleman that he is, allows people to have what they want despite his desire - and so the impetus for their going to hell is solely in their hands. People in the camp are usually Amyraldian in their theology, saying that Christ died as an atonement absolutely for the elect, and as an atonement conditionally for the non-elect.
If God actually 'passes over' the non-elect, as we believe, then it seems to me that he is making a definite decision to fore-ordain their destruction by not decreeing their salvation. Sure, the means to that end are absolutely active on God's part for salvation, and passive on God's part for damnation. God simply has to leave the non-elect in their sins in order for them to find their destination, whereas he absolutely has to work a miracle in the elect to bring them to his intended destination for them.