redundancy
use of a number of critical components for securing one or more functions of a system with the intention of increasing its reliability, usually in the form of a backup or fail-safe design
lockstep
method of fault-tolerant computing by running operations at the same time in parallel
redundancy
in information theory, extra bits transmitted without adding information
Dual modular redundant
in reliability engineering where system components are duplicated
error detection and correction
techniques that enable reliable delivery of digital data over unreliable communication channels
dual SIM
feature of mobile phone (or other devices) enabling two SIM cards