Preheat the broiler. Heat the olive oil in a large nonstick skillet over medium-high heat. Add the sausage and cook, breaking it up with a wooden spoon, until browned and cooked through, about 7 minutes. Transfer to a paper towel?lined plate.
Melt the butter in a small skillet with the garlic, oregano and red pepper flakes. Split the whole pack of attached dinner rolls in half horizontally. Place the top and bottom halves cut-side up on a baking sheet. Brush the cut sides with all but 2 tablespoons of the garlic butter; season with salt. Broil until toasted, 1 to 3 minutes. Remove from the oven and preheat to 400 degrees F.
Scatter the cooked sausage and pepperoni on the bottom bread piece. Dollop with the marinara, then top evenly with the mozzarella. Cover with the top bread piece, then brush the roll tops with the reserved garlic butter and sprinkle with the parmesan. Bake until the bread is toasted and the cheese is melted, 12 to 15 minutes.