There is an attachment that does the same thing without buying a mod.
Indeed, the dual carto adapter works quite well. Plus it has a mouthpiece that fits over both cartos and turns into a single mouthpiece, so you don't have to figure out a way for your mouth to seal around two separate drip tips.
Honestly I don't know how well that mod in the OP would perform. I've used my dual carto adaptor on straight battery voltage devices, and it's pretty cruddy. But running the dual cartos at 5v works wonderfully, 21 watt vaping in theory.
Just like with dual coil cartos, you need to pump a lot of power into them to get them to "wake up" and perform better than a single carto. You could likely get a Vamo and the dual carto adapter together for a price equal to the mod in the OP. And it would perform drastically better.
