Warhol’s ‘Homage To Marcel Duchamp’?

This interesting Polaroid from the Warhol Estate just turned up at Swann.
It’s apparently titled Urinal (Homage to Marcel Duchamp), which would make it kind of fascinating. But there’s nothing except an estate authentication stamp on it, no title, date, signature, nothing. So where did the title come from?
It’s also on a previous owner’s website, without the Urinal or the parentheses in the title. The provenance says it came from the tag sale portion of Sotheby’s 1988 Warhol auction.
verso of this Warhol Polaroid, image via alpha 137
But it also says it’s a photograph of a urinal, when it is in fact an awning over an arched window. And what looks like adhesive on the back runs along one side, here the left, which would normally be the top of a Polaroid image. So how was it oriented again?
Assuming it’s what it says, though, it’s interesting that Warhol made his homage to Duchamp’s famously inverted sculpture by inverting an image. Or an object, a print (Polaroids are one-offs).
[Also worth noting: in 1973 Warhol bought the prototype for Arturo Schwartz’s 1968 Fountain edition. And Dakis bought it from the 1988 auction.]
update: Homage To Marcel Duchamp is a lot of reference for one Polaroid to bear. And it is probably worth considering how many Polaroids Warhol shot in his lifetime: approximately fifty hundred bajillion. And do they all have titles? Do any of them? What is another Polaroid with a title?
Sale 2431 Lot 126 ANDY WARHOL, Urinal (Homage to Marcel Duchamp), est $3-5000 [swanngalleries]