In dual crossfire both the intigrated and the discrete works together, only if the clocking on the dedicated card is strangled to clock below or equal to the rating of the intigrated or else the system will override and ignore the intigrated card.
If you think it's the Directx you can upgrade to windows 10 since it was early announced by microsoft that windows 10+ will have support for dual graphics with the next generation, twin dual graphic motherboards (quad core graphics).
Search for "Dxdiag" and all the important information about what the computer supports are seen, includes resolution and other useful information. Try to put all settings the same way for both energy saving and power consuming graphics. Make sure the strangle feature is on or remove the crossfire entirely.
I have same problem with my dual gpu laptop, my laptop is Lenovo Thinkpad E455 Hia with R6 + R7 M260DX
in device manager, i check my gpu detail in R7 m260DX, in Hardware IDs i found code of R7 m260DX is PCI\VEN_1002&DEV_6664&CC_038000
after i search on google, i found the driver is R5 M200 series not R7 M260DX
can someone help my gpu
i play dota 2 in lowest setting and i get 30-50 FPS