It seems that when shift-clicking to craft when you have enough ingredients for 1 craft but not 5 the recipe results will still be given to you but without subtracting any of the cost.

This is from within the normal vanilla style crafting menu (i.e. within inventory menus, not from workshop table).

Log doesn't appear to have any details for the issue, but it at least mentions version numbers. (everything relevant should be latest version anyway)
SMAPI-latest.txt

I've also just confirmed this occurs with the workbench too

Just ran into the dupe bug myself, and in case anybody else runs into it, I can confirm that using "Craft from Workbench Distance" conflicts with "Craft from Chest Distance" and specifically metal bars twice for some reason. Setting "Craft from Chest Distance" to Inventory fixed it for me. Don't know if this info will help with squashing this bug, but figured I'd give the little bit of info I was able to find.