The ornamental design for an ledsingletwin-tube light bulb, as shown and described.
FIG. 1 is a perspective view of an LED single twin-tube light bulb showing my new design;
FIG. 2 is a front view of FIG. 1;
FIG. 3 is a rear view of FIG. 1;
FIG. 4 is a left side view of FIG. 1;
FIG. 5 is a right side view of FIG. 1;
FIG. 6 is a top view of FIG. 1; and,
FIG. 7 is a bottom view of FIG. 1.
The broken lines in the figures form no part of the claimed design. FIGS. 1-5 have been shown broken away for ease of illustration and to show the indeterminate length of the article.