Make the Pie Dough First: In a food processor or with a pastry cutter, mix the flour, salt, and sugar. Next, add the cold butter and cream cheese pieces a third at a time. Add the cold half and half a tablespoon at a time, pulsing in between each addition. Turn the dough onto a parchment-paper-lined work surface and form into two disks. Chill in the refrigerator.
Make the Cherry Pie Filling: Combine cherry preserves, salt, tart cherries, and cook until thick. Add cornstarch, butter, and vanilla extract.
Make the Blueberry Pie Filling: Combine blueberry preserves, fresh blueberries, lemon juice, and salt. Cook until thick, then add cornstarch and butter.
Roll Out Dough: Roll out the larger disk of pie dough, press into a pie plate. Fill distinct sections with cherry and blueberry fillings. Use aluminum foil as a barrier between the fillings. Create a flag design on top using dough strips and stars. Brush with egg wash, sprinkle with sugar, and bake.
Bake the pie at 375°F for 20 minutes, then decrease heat to 350°F and bake for another 30-35 minutes until golden brown.
