Technically you don't need to touch the naked wire, you only need to remove (carefully) the outer insulation and have the two (still insulated) wires separated for a few centimeters.

Then there are splitter clamps.

The most common ones are used (low voltage) on cars and motorcycles, they look like these:

https://www.mesconnettori.it/index.cfm/it/ricerca/?flbr=ruba...

But there are professional ones, suitable to 110 or 240 V example:

https://www.techno.it/en/products/all/thb-370-a2a/