Variants of a mold are catalogued separately, so each one has its own sets and minifigs. Check these too if something you expect is missing here.

• 646 Window 1 x 6 x 2 with Shutters this part is a alternate of it
• 646ac01 Window 1 x 6 x 2 with Shutters (old type) with Extended Lip and Solid Studs, with Fixed Glass this part is a alternate of it
• 646c Window 1 x 6 x 2 with Shutters, without Glass for Slotted Bricks this part is a alternate of it