As it happens, in our solar system the two closest worlds with reasonably strong magnetic fields are Jupiter and its moon Ganymede.
And the interaction between their two magnetic fields has a lot of interest to those interested in magnetism.
And I can imagine that in some situations the interaction between the two magnetic fields could suggest plots of science fiction stories.
For example, a vehicle using magnetic interactions to travel in space - which would probably be very slow to accelerate or decelerate or change course, but might save on fuel for a satellite needing to keep in position, for example.
Some macroscopic lifeforms have been levitated by magnetism. I doubt if your world could have magnetic fields strong enough for that. But possibly interactions between the magnetic fields of the two planets might be strong enough to levitate and move microscopic organisms important to the plot.
I strongly believe that most Earth like planets will not have magnetic fields strong enough for the interaction between the magnetic fields of two twin planets to be important. But a sufficiently clever writer might be able to give the planets magnetic fields as strong as possible without being lethal to life, and then find a a way to have some effects of their interaction important to the plot.