The basic requirement is to send two portions, but what exactly constitutes “two portions”? The Shulchan Aruch states “two portions of meat.” Based on this, some understand that even one large piece of meat that can be divided into two reasonable portions would suffice, and indeed Eshel Avraham (Buchacher, last comment in OC) entertains this possibility. The Mishnah Berurah and many other posekim do not discuss the need for different types of food. Others understand (and this is the accepted halachah) that while two “types” of food are needed, the same item can be used as long as there are two distinct tastes. For example, Rav Auerbach (Halichot Shlomo 19:12) says that one can use two pieces of chicken—a top and a bottom—because they do not taste the same. Rav Nachman Kahana (Spinka Rebbe, late nineteenth century) suggests (Orchot Chaim 695:12) that in the Talmudic story, Rabbi Yehuda Nesiah fulfilled his obligation by sending meat because each limb of the animal tastes different. He quotes Rav Moshe Falk (nineteenth century) who discusses whether two types of wine, such as red and white, are considered two different types of food. Rav Falk (Tikkun Moshe, Purim 93a) also wonders whether roasted and cooked food would be regarded as two different types. He concludes that, based on the wording of the Shulchan Aruch, it would appear that they are indeed different. Rav Yosef Teomim (author of Pri Megadim), in analyzing the Talmudic story (Rosh Yosef, Megillah 7a), implies that two different fruits are considered two types of food. Rav Yitzchak Yosef (Hilchot Mishloach Manot 6) rules that one can send two similar pieces of raw chicken (or meat) because they can be cooked in different ways. The accepted halachah seems to be that two cuts of meat (i.e., from different parts of an animal), even from the very same animal, or two different fruits or types of wine, are regarded as two types of food and therefore can be used to fulfill the obligation of mishloach manot.
There is no source anywhere indicating that the two foods must have different berachot; in fact, from the above examples, it is clearly not the case. It is possible that this notion became popular as many were confused about what constitutes two types of food. To avoid confusion, they began sending food from two different categories of blessings.
Ari Z. Zivotofsky, “What’s the Truth about . . . Mishloach Manot?”, Jewish Action (Spring 2014), 83-84.