I'm not sure what you're talking about here.
I have never seen an operating system where one user would have multiple cursors to edit text at multiple locations at the same time. For that, you'd need 2 sets of keyboards (and mice).
Of course, there are systems where multiple users can work on the same file parallelly (e.g. MS Office offers this for Word, Excel, etc), but this is a multi-user system.
Problems are usually fixed one by one not "at the same time".
Please, specify what you're after.