Dual GPS RTK navigation

We are wondering what happens if we have both a Here RTK and a normal Here 2 non-RTK GNSS receivers onboard, running Copter firmware.
Searching through forums, seems nobody tried this approach.
We know that two regular GNSS receivers can work in blend mode, or simply in “best one” mode, but we’re not sure what the behaviour will be having RTK active on one.
May we assume that, in “best one” mode, the RTK will be used most, due to its better accuracy?
Also will the “blend mode” sorta ruin the accuracy of the RTK one?