Eagletac and Fenix both have that configuration. I had the first version of the Eagletac M2XC4. I found that it sat on the shelf too much so I sold it.
You don't really need to parallel to do that.I cant afford a custom job. I need something that lasts longer than 3 hours, has rechargeable batteries and puts out more than 150 lumens without overheating every 2 minutes.:thumbsup::thumbsdow