Due to is understood as caused by.
Back in the dark ages of the 1960s we were taught to distinguish between necessary and sufficient causes.
If B and C are each, independently, sufficient causes of A, this may be expressed most succinctly by
A may be due to either B or C.
The may be is not strictly necessary; but it is to my mind preferable to is in order to avoid misunderstanding.
If B and C are both necessary causes of A but neither is a sufficient cause in the absence of the other, the use with both is accurate but, again, may be misunderstood; it should be qualified with an additional phrase (here bracketed—another phrase may suit the particular context better):
A is due to both B and C [operating together].
It gets more complicated if a third cause, necessary or sufficient, is involved.