Yes mostly all the content that comes in Dolby Vision also supports HDR, while HDR is a free certification for which manufacturers don't need to pay anything to anyone, for getting Dolby Vision Certifications manufacturers pay to Dolby to certify their TV's.
Currently I am using Fire TV Stick 4K which supports Dolby Vision alongwith my TV so able to play the content in DV.
But if I had been using Mi Box 4K even I would be getting HDR as Mi Box doesn't support DV while my TV Supports it