The ornamental design for a rectangularbeveragedispensercover, as shown and described.
FIG. 1 is an isometric view from the top, front and one side of a
rectangular beverage dispenser cover showing my new design; and, FIG. 2 is
an isometric view thereof from the bottom, back and the other side
thereof. The rectangular beverage dispenser illustrated in phantom line in
FIG. 1 represents environment only and is not a part of the claimed
design.