We claim the ornamental design for a multi collar brush holder, as shown and described.
FIG. 1 is a perspective view of a multi collar;
FIG. 2 is a top view of the multi collar;
FIG. 3 is a left side view of the multi collar;
FIG. 4 is a right side view of the multi collar;
FIG. 5 is a front view of the multi collar;
FIG. 6 is a rear view of the multi collar; and,
FIG. 7 is bottom view of the multi collar.
The broken lines and the areas within the broken lines illustrate portions of the multi collar makeup brush holder and form no part of the claimed design.