I have a problem where I needed dual USB jacks for charging up to two tablets. The area I need power doesn’t have an electrical outlet so I have run a two prong extension cord. You can buy electrical outlets these days with built in USB ports but this wasn’t an option in my situation.
There are a lot of dual port chargers on ebay but you do have to worry since most cheap chargers do not have UL safety certification. You need to pay more for a name brand product. You don’t want to start a fire to save a few bucks. Chargers are not created equal though they may look the same on the outside.
To charge the larger batteries of tablets, you need one that outputs 2-2.4A which is more that a standard PC USB port. Checking specifications, sometimes it’s not clear if on dual port chargers, both ports output that much current.
I was able to find the Blitzwolf BW-S3 at Banggood shipped from China decently priced. Their website indicates their products are safety certified though there is a chance of getting a counterfeit item. The charger arrived fairly quickly and is working well.