The ornamental design for a dual flowerholder for crypt covers, as shown and described.
FIG. 1 is a top, front, left side perspective view of a dual flower holder for crypt covers showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a back view thereof;
FIG. 4 is a left side view thereof, the right side being a mirror image thereof;
FIG. 5 is a top view thereof; and,
FIG. 6 is a bottom view thereof.
The broken line showing of a rosette and the peripheral thickened dashes indicating the boundary are included for the purpose of illustrating environment and form no part of the claimed design.