The rabbis of the Talmud were certainly aware of Zoroastianism. You'll find references to fringe groups who believed in "שתי רשויות", "two domains"; effectively, one deity in charge of good things, and a different one in charge of bad things. That's why the mishna says that a chazan whose text is "Modim, Modim" should be immediately removed: if you lived in the Middle East around the year 150, that was a good sign you believed in two different deities to thank.
Isaiah writes that God "fashions light and creates dark, makes peace and creates evil." This dichotomy features heavily in Zoroastrianism, and thus in response our prayer texts say instead: "makes peace and creates all", stressing that everything comes from one God.
Quite frankly I would assume that we would treat it as avoda zara, at least from our standpoint (e.g. something used in their worship would be prohibited from our benefit). It was very common in the times of the mishna yet we don't find the mishna offering any distinction between flavors of non-Jewish worship at the time; what's more the mishna Shabbos 2:5 speaks of heathens who won't let you have your shabbos candles lit; R' Ovadya miBartenura comments: "because of idolaters -- there were Persians who, on their religious holidays, would ban all flames unless lit within their temples." I'm told that was the Zoroastrians. (Or at least early ancestors.)