These things exist, using trade names like chipkill or lockstep memory. Though they don't need to sacrifice half of the memory chips to get good error recovery properties.
Note that this is still not end-to-end protection of data integrity. Bit flips happen in networking, storage, buses between everything, caches, CPUs, etc. See eg 
 https://arxiv.org/abs/2102.11245 Silent Data Corruptions at Scale (based on empirical data at Facebook)