Amoraim

When the confrontation between Rebbe Yossi Barabi Chanina, and Reb Yehoshua Ben Levi is brought I think that the guy writing our gemara just brought these two opinions to start a conversation. Reb Yehoshua Ben Levi was a first generation amora living in Israel and I think Rebbe Yossi was second or third generation of amoraim therefore they can't be arguing in real time. I was just wondering if all gemaras are written like this.