Do Wirt's Coins Stack?

I already have one coin. Now I have the 3 splinters needed to make another but I don’t want to transmute the splinters at the cube if I can’t have more than 1 in my backpack. Thanks.

They have been able to stack from day 1 of the season; at the moment, my Rogue has 3 from pre-patch.

Thank you. 20 characters