I see now, looking at the photo yes one has the top surface of the rests flatted and polished while the other doesn't. I'd still say this is normal variation and the unpolished one is definitely not from the trash! Remember these were likely in production for several years and could have been finished by different teams or for different customers. While Sabino isn't my main area of interest, I've handled quite a lot as I used to deal in 30s pressed glass. As I said before, the older pieces are very variable in finish. If you can find his contact details, Philippe Decelle is the man to ask about Sabino, he compiled the catalogue Raisonne and also the book Opalescence Le Verre Moule des Annees 1920-30.
What an awful response from Sabino Art Glass! I had a rather brusque reply from them when enquiring about buying, but nothing as rude as that. I've never done business with them as I disliked their attitude then and I can see it hasn't changed since...
Sue, regarding your butterfly, if you post a photo of the mark I may be able to tell if it's older or newer. The mark on more recent production often is constructed of broader strokes as the engraving tool has a greater tip diameter. Older Sabino has a variety of marks; I've seen etched, moulded, diamond point incised and engraved.
I love opalescent glass too. I used to have a very big collection, mainly Jobling, Barolac and Verlys. I've since downsized a great deal but still have a lot of Jobling and have kept my favourite Barolac & Verlys pieces and one or two bits of Sabino including a rare paperweight made for the French shipbuilder Augustin Normand and a very unusual and unmarked blue cased opalescent vase coquilles.