what reuseExistingChunk: true means, can give a sample?

Do you want to request a feature or report a bug?
document not clear

What is the current behavior?
what optimization.splitChunks reuseExistingChunk: true means, can give a sample?
If the current behavior is a bug, please provide the steps to reproduce.

What is the expected behavior?
can give a sample? reuseExistingChunk: true or false, what different?

If this is a feature request, what is motivation or use case for changing the behavior?

Please mention other relevant information such as the browser version, Node.js version, webpack version, and Operating System.