Is it ok to use a pcie dual splitter as an extender one of the dual 6+2 pcie cable ?

Long story short I have a pcie cable with 2 – 6+2 pins , so they provide upto 150watts each ( 300watt/288 watt for a pcie cable) , so I have a GPU and a riser and want to connect both using the same PCIE cable as it has 2 6+2pins , now the GPU am powering comes well under 150watts TDP and the riser 75watts , so am thinking it should be enough , but the problem is the 6+2 pin isnt long enough to connect to the riser and the other one all the way upto to the GPU

So am thinking of getting a 8pin to dual 6+2 pin splitter and use one of those 6+2 pins to connect to the riser /GPU, as only one is connected the one 6+2pin would provide power upto 150watts right ?