Check by pairing a DUAL R3 with my account, maybe I know your issue,
the DUAL R3 display two tiles in eWeLink web correspond to two channels, so you need to download the historical data via each setting separately.
One more suggestion if it is possible…
Each time that I click on a DualR3 Item and try to get the device Settings, then I’m not aware about which of the two channel I have opened.
I was thinking that maybe adding the info about which channel it is selected this will help the final users to don’t lose the focus.
I prepared a screenshot as suggestion, I hope that it will help