It's very common for larger projects requiring sophisticated algorithm development coupled with demanding runtime requirements such as high throughput, low late

It's very common for larger projects requiring sophisticated algorithm development coupled with demanding runtime requirements such as high throughput, low latency, or high reliability. In such cases, the separate toolchain inefficiency can be justified by higher developer efficiency and the advantage of having two separate code bases developed two ways by two different teams. The two versions can be compared functionally to find many errors that would otherwise be missed due to bad assumptions, library issues, compiler issues, incomplete test coverage, etc.