The ornamental design for a double paint roller, as shown and described.
FIG. 1 is a perspective view of a double paint roller, showing my design.
FIG. 2 is a front elevational view;
FIG. 3 is a rear elevational view;
FIG. 4 is a side elevational view from the right side;
FIG. 5 is a side elevational view from the left side;
FIG. 6 is a top plan view;
FIG. 7 is a bottom plan view; and,
FIG. 8 is a front elevational view with rollers assembled onto each paint roller.
The broken lines shown in the drawings are for the purpose of illustrating unclaimed portions of the double paint roller and form no part of the claimed design.