It’s very easy to use
The MagSafe Duo Charger with an unclear price has already appeared on the Apple website, and it remains to wait for the start of sales. Recall that in the United States without taxes they ask for 130 dollars.

Charging Apple MagSafe Duo Charger for 130USD lit up on video
In general, it can be assumed that the accessory will not become very popular because of the considerable price, because a regular MagSafe charger is more than three times cheaper.