Should they be merged?
Possibly. There's only one counterexample I can think of (Is execution of sync(8) still required before shutting down linux? -- and it's lousy counterexample)
If no other counter-examples come up we can untag that one and make with the merging. (synchronization <- sync)
Do either of them need to exist? If it were the only tag on a question, it wouldn't do much to categorize it.