  Motivated by [Bor] and [Mar], we show the equality $\left([X] - [Y]\right)
\cdot [\mathbb{A}^1] = 0$ in the Grothendieck ring of varieties, where $(X, Y)$
is a pair of Calabi-Yau 3-folds cut out from the pair of Grassmannians of type
$G_2$.
