I am editing a special issue for the reputable Journal A. My special issue is now closed and I am still running the paper reviews. Much to my surprise, I discovered my CFP is plagiarised word-by-word and it is now online in another reputable journal B by different editors. I understand that calls for papers are not original papers but is it acceptable to copy someone else's published CFP word-by-word without proper acknowledgment? Would this create any problem for me when I write a preface for the published papers in my special issue? What would you do if you were instead of me :)
The call for papers is normally written by the guest editors of the special issue, so they are probably the ones at fault here. If, as you say, that other journal is reputable, then its editor (i.e., the usual editor, not the guest editors of the special issue) probably doesn't want to be seen as complicit in such a disreputable activity as aping another journal's special issue selection and plagiarizing its call for papers. I'd fire off an e-mail to them describing what has happened and asking politely but firmly for an explanation. If they shrug you off, then the journal is obviously not as honourable as you had imagined, and you can then decide whether to drop the matter or to escalate it (for example, by getting in touch with the journal's publisher, or by publically naming and shaming them). If you do choose to escalate, you might want to first discuss this with the editor and/or publisher of your own special issue's journal.