The ornamental design for a storagematbag with cap and two handles, as shown and described.
FIG. 1 is a perspective view of a storage mat bag with cap and two handles showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken lines in the figures are for the purposes of illustrating portions of the storage mat bag with cap and two handles that form no part of the claimed design.