Heat oven to 375°F. Separate dough into 4 rectangles. Place on ungreased cookie sheet. Press each to 7x5 inches, firmly pressing perforations to seal.
Spread 1 tablespoon marinara sauce on each rectangle to within 1/2 inch of edges. Place 8 slices of pepperoni in center of each rectangle; top with 1/3 cup cheese and 8 more slices pepperoni. Bring ends up over filling, overlapping about 1 inch. Press edges with fork to seal. Brush each sandwich with water, and sprinkle with Italian seasoning.
Bake 13 to 15 minutes or until golden brown. Immediately remove from cookie sheet. Serve warm.