Safety or bladed

[Downunder Kilt]

I have carried a knife since I was a child, my school allowed sheath knives. A strange concept in this day where all knives are considered weapons not tools. It did allow me to realise that there are no dangerous weapons, just dangerous people.
I carry a Boker/Magnum sgian dubh supported by my brace, it's kept sharp and been used a few times. It's a tool.

Just wondering when the sgian dubh became a dagger, Would greatly appreciate any historical details that shows it was twin bladed rather than a single bladed knife, Cheers