The ornamental design for a double loungecabana, as shown and described.
FIG. 1 is a side view of the present invention
FIG. 2 is a top view of the present invention.
FIG. 3 is a bottom view of the present invention.
FIG. 4 is a side view of the present invention.
FIG. 5 is a front view of the present invention.
FIG. 6 is a back view of the present invention; and,
FIG. 7 is a side perspective view of the cabana.
All broken lines on the Figures form no part of the claimed invention. Broken lines include dotted lines, such as those on the deck surface of the cabana, dashed lines, such as the frame, and dot-dot-dashed lines such as the umbrella, which are present only to demonstrate an environment of use.