I was trying to collate some tags about randomization and noted that random-allocation seemed to be the parent-tag of preference. As I searched tags for instances of "random" I noted some hits for randomized-experiment. I was about to propose the tag as a synonym, but noted that it was already merged into random-allocation. When I navigate to the questions tagged as such, the excerpt, wiki, and related questions are all those of random-allocation.
So it prompts the question: why do tag synonyms show up in a search?