I just thought I'd chime in with an answer to the OPs questions since everyone was super lost on this one, and this thread turned up in the Google searches.
I have both a relatively new Dahua 4K Color (4k-T) and a Hikvision 4K Colorvu.
While the Dahua app makes it look like their cameras can record simultaneous dual streams (Go to DMSS app, 3 dots on the camera > Stream Setting > choose which stream to use for live and playback), they only record on stream, and if you choose the low quality stream for playback in the app, it will in fact playback the HQ stream.
Sadly, you can only record one stream onboard with the Hikvision as well.
So this means if you record the main stream onboard, you are stuck with only being able to play back the main stream, including on the mobile app. This obviously results in high bandwidth usage, choppy, and delayed playback over mobile networks unless you have your recording parameters (fps, resolution, quality) turned down or have some extreme bandwidth through your mobile provider. This is clearly a major deficiency for anyone using local playback and recording, and not using an NVR that can record and play dual streams.