I like this a lot more, because it captures whether two things are necessarily the same or just happen to be currently the same.

A common "failure" of DRY is coupling together two things that only happened to bear similarity while they were both new, and then being unable to pick them apart properly later.

> then being unable to pick them apart properly later.

Which is often caused by the "midlayer mistake" https://lwn.net/Articles/336262/