Different Versions of classical works

[Mike]

I have two different collections of Sherlock Holmes original stories. The were published at different times and they have different editors and introductory contributors. I can understand why they are combined as different editions of the same book, but I wonder if there is ever the case where they would NOT be? What if the two volumes were to divide the collected works into two different selections? Do the editors or introductory or prefacing contributors change this in any way?

[Sandra]

They wouldn't/shouldn't be combined if they contain different stories.

Editors or Forewarders shouldn't make any difference as they are not a substantial difference.