The speech I was adapting is repetitive in that way: Vizzini infers various things in turn about Westley's mental processes, and ends each inference with "so I can clearly not choose the wine in front of me/you".

So yes, I hear you, it would have been nice to do some of the variation you describe. However, in this case, it came into direct conflict with retaining the sense of the source material, and I picked the latter. I'm not sure how I could have usefully added such variation without abandoning the whole attempt and writing a villanelle about something completely different instead.

You've already lost that ultra-strict repetition, though, because the two lines don't match.

Here's what I just threw together:

Choose the wine that sits in front of me?
Not I! But wait. Is this a bluffing play?
The wine in front of you it cannot be.

So now I watch, until some slip I see,
Some betraying glance so that I then may
Choose. The wine that sits in front of me

Is far from you, where poison ought to be.
Still, though, you think you're strong. Would you assay
The wine that sits in front of you? It cannot be

That complex, so I must not, you'll agree,
If I would see the sun go down today,
Choose the wine that sits in front of me.

You've brought this poison over land and sea.
Exotic fare indeed, and so I say
The wine that sits in front of you it cannot be.

This puzzle would stump greater minds than me:
Though doom awaits them if, foolishly, they
Choose the wine that sits in front of me,
The wine in front of you it cannot be!

Oh, just noticed I rhymed 'me' with itself in the last stanza. Nasty. Sorry about that.

S.

(And 'be' in the third, but that's less of an issue because of the enjambment. The 'me' lines are both endstopped, which makes it harsh).

S.