I think that Seguso did some sommersos in the purple color scheme, but they are a more muted purple than your piece seems to show. The only vase at the Wright auctions you listed that I would agree 100% to be Poli is the "valva" vase - the one that gets very thin at the top. This is a known Poli form and I don't think anyone copied it. To me, this vase is more technically perfect than yours. Also, there is something about the thickness of the rim of your vase that bothers me - I've seen similar work on newer pieces.
All that said, it's really, really hard to tell what is old and what is new with sommersos, as they have been in continuous production since their introduction. Even experts have trouble telling the difference sometimes. I'm not sure your piece is new, or even that it's not Seguso. I am only telling you my gut reaction, based both on the colors but more importantly the form, which to my eye, looking at a photo, seems somewhat sloppy. Of course, I'm only looking at a photo and might change my mind completely if I were to see the piece in person.