Apparatus for filling containers with two products from different sources, using a rotating volumetric filler which picks up first one product then the other, and discharges them both simultaneously into a container. The filler uses a pair of concentric pistons, the central one of which is retracted to pick up the first product as it rotates over an arcuate slot beneath which the first product is stored; the outer, cylindrical piston is then retracted to pick up the second product as it rotates over another arcuate slot beneath which the second slot is located. Both pistons are later extended simultaneously to discharge the combined product into the container. Since the two products picked up by the successive retractions of the two pistons are held beside each other, a more uniform mixture of the two products is obtained than if they are picked up one above the other by a single piston.