If you are looking to convert a single faucet kegerator to a dual faucet, there are key components you will need. They can be purchased at a local beer supply shop, or at our retail partner, kegerator.com
Things you will need:
Manifold to split CO2 lines
a 3" Dual Tap faucet
An additional CO2 line
An additional beer line
You will also need additional clamps, neoprene washers, and duck bill washers (check valves)
When you start buying all of those parts individually, you would save money and end up with a few spare parts such as a coupler, faucet, and regulator if you purchased an entire kit. I will link to that kit below.