On Blogger, I can schedule blog posts for future publication. I can also back-date blog posts. Theoretically, if I had another Blogger account, I could have them making blog posts at the same time. But what would be the point of that? There could be some deceptive value to post back-dating: when the first incident of Wikipedia-related homicide occurs, I could write up some blog post with some sketchy approximation of what actually happened and back-date to say, a month prior. Then my blog post would seem prophetic.
On Wikipedia, as far as I know, there is no way to schedule edits nor back-date edits. At least I can say such tools are not available to the average Wikipedia user. But that doesn't mean that Wikipedia's most brutal warriors don't find ways to both schedule edits and back-date them. Scheduling is probably easy, as computers offer us plenty of ways to command them to do something at a specific time in the future. Back-dating edits would certainly be more work, in part because it requires access to the server itself. But Wikipedia's most vicious warriors definitely have such access.
Although those brutal bastards can have many sock accounts and give the appearance of independent users by having overlapping edits, that means nothing. They can just as easily declare a bunch of you to be operated by single sockmaster.