The original design? The ancient Sumerians believed the god Enlil invented the mattock. The "original" design appears to have been made from antlers just after the last Ice Age. It's so old a tool that no one even knows the language origin of the name.
That said, his does appear to be a forged and chisel split eye design. It's also more a "cutter" mattock style (aka "grub axe") than a pick head mattock. So it is from the time of blacksmiths; and made by a smith that didn't have/use a standard handle mandrel. (But that covers a long, long time).