Two redundant cardiovascular systems that don't work together, presumably in such a way that a heart attack or exsanguination in either is lethal (as opposed to modular redundancy for improved reliability, which mostly isn't relevant at the software level).
C++ isn't really one language, but a language family with dozens if not more dialects. If you read some codebases from different places, you will sometimes, or even often, barely recognise what's going on (unless you are an advanced user).
In C++, people very much tend to pick a subset, so different pulses beat concurrently, if you will.