Mods:
alcatrazcore-1.0.4
notreepunching-2.0.12

Forge Version:
forge-1.12.2-14.23.5.2768

If I combine two saws or two wooden clay tools together (presumably to combine their durability) I get a tool at the cost of only one durability of each of the input tools, rather than consuming the input tools. Essentially, infinite tools. This is especially problematic in modpacks with metal recycling, as it allows by extension infinite metal and infinite furnace fuel.