It is not really the case that a mag can "overpower" the other mag.
Except in the case of a single shaft dual mag (like the Series 3000 one that I have) there is no connection between the two except the accessory drive gearbox and if that gets shredded then your camshaft will prob99 also develop a mind of its own
What can obviously happen is that a fault in one mag, which causes an
earlier than normal ignition, can mess up the engine, by igniting the stuff a lot sooner. The fact that the other mag delivers a spark at the right time is of no help.
The dual-mag redundancy assumes that a mag failure will be either (a) a total failure to deliver a spark (probably the most common failure mode) or (b) a late delivery.
Even if you replaced the mags with dual electronic ignition, you still have the same problem because if e.g. the sensor slips on its mounting you can get an early spark with that too. One could devise clever ways to block an obviously early spark, however.