In case the links above disappear or for those without a catalog handy, here is the stamp under discussion:

I took a look at about 50 used copies I had to survey their inking accuracy.
As noted above, blue low to tinge the head and back of the right chick:

Yellow ink high partially coloring the bottom of the arc at the base of the adult's leg:

Green high to make lower portion of the chicks mostly green:

Yellow very low to make much of the grass yellow:

Interesting? Yes.
Collectible? yes.
Catalog noteworthy? No.