I think it could qualify as poly if you're warning everyone that you're not exclusive, and if you're open to serious relationships with the people you date. If it's casual sex, it sounds more like swinging to me.
But I don't know, I've never dated around, and I think most people would expect you to be dating only them if you're dating them, no? Even though I'm poly, if I date someone who tells me they're single, I'll interpret it to mean they're not seeing anyone at all. To me, dating means you're not single anymore (I guess you could argue "but then nobody could tell you "I'm single" and be telling the truth, since by dating you they stop being single" but I see it as a case of "I'm on a desert island". It's not desert since YOU are on it, but that still works. If you meet someone else there, though, it's not a desert island anymore.)