One sensor per MCAS means that only one sensor is used at a time, so if it is installed incorrectly or is faulty. The faulty data is fed into the MCAS. This is what caused the crashes.
The more expensive option packages included dual-AoA sensors. Two AoA sensors per MCAS, and then an AoA disagree alarm that would alert the pilot that the AoA sensors are not in agreement.
In reality these systems were meant to be redundant, and not linked together, so they're taking a sensor meant for a failover system and combining it into a single system to create this 'workaround'
https://boeing.mediaroom.com/news-releases-statements?item=1...
The AoA sensors on the standard model were meant to be redundant, not work together. Boeings fixes are making the sensors work together, while sacrificing what they originally designed as redundancy.
Boeing is intentionally trying to suggest what you are which frames the problem as a mistake