I am not an expert grower of blood oranges because I live in the northern part of Italy and blood oranges (or Tarocco varieties as we call them) are intensively growth in the southern Italy, but I can provide you this link with a lot of description of italian cultivars and every time you see written
Alternanza assente means no alternancy.
https://www.vivaimessina.it/Scelte-varietali-in-agrumicoltura.pdfAccording to that nursery, except a couple of them, no alternancy looks like it is pretty common for Tarocco: Gabella, Gallo, Ippolito, Lempso, Meli, Messina Rotondo, Rosso VCR, Sant'Alfio, Sciara, Sciré, Tapi, TDV.
They are all commercial varieties and not rares at all, but in this season maybe Ippolito, Lempso, TDV, Tapi, Gallo are among the most sold in the markets, in Sicily most of the time you'll find the variety names than in northern supermarkets but some are easily reckognisable: for example Lempso for the red peel, Sant'Alfio because of the double fruit like ombilicate oranges and so on.