For the homemade pici pasta: Whisk the flour, semolina and salt together in a large bowl. Heat 1 cup water in a small saucepan to a simmer. Add the olive oil and just 2/3 cup of the water to the flours and mix to combine. If the dough still looks a little dry, add more water, a small splash at a time, until the dough comes together. Gather the dough into a ball and transfer to a work surface. Knead the dough until elastic and somewhat smooth, about 3 minutes. Wrap in plastic wrap and let sit at room temperature for at least 1 hour and up to 4.
Lightly flour a work surface with semolina. Divide the dough in two and roll each piece out to be about 1/4-inch-thick or a little less. Cut all of the dough into 1/4- to 1/2-inch-wide ribbons. Working one ribbon at a time, use the palms of your hands to roll it into a tube shape, pressing firmly to thin it out slightly and make elongated, uneven, wormlike strands. Repeat with the remaining pasta ribbons, transferring the pici to a sheet tray and lightly dusting with semolina as you go.
Bring a large pot of salted water to a boil.
Add the pici to the boiling water and cook until al dente, about 4 minutes. Reserve about 1 cup of the cooking water, then drain the pici.
For the carbonara sauce: Put the pancetta in a large skillet over medium-high heat. Cook, stirring occasionally, until the fat has rendered and the pancetta is crisp, 6 to 8 minutes. Transfer the pancetta to a paper-towel lined plate with a slotted spoon. Pour about 1 tablespoon of the rendered pancetta fat into a large bowl.
Add the eggs, Parmesan, pecorino and a generous amount of pepper to the bowl with the fat and whisk to combine.
Add the cooked pici to the bowl with the cheese and egg mixture, then add a splash of the cooking water and the pancetta and toss until creamy and well coated. Add a little more pasta water to loosen if desired.
Add to a serving dish and top with parsley. Serve with additional Parmesan.