The both mean two things that can work together or at the same time

Dual is used for things that Work together and it Doesn’t make difference if one of them works or Not

Double is used for things that Work with each other and the Function doesn’t work Without one of them

A dual SIM cards mobile.(It work without one of them and it doesn’t make difference.)

A double pair of wires consisting of phase and neutral charge.(The wires don’t work without one of them.)