Option to leave out n.d. with some source citations
There are times when the date has been left blank on a source in Zotero because the year has been used in the source already, as part of the title and/or archive location. The abbreviation n.d. is not really appropriate for those occasions. Is there a way to override n.d. from being forced into the citation in CMOS?
Answer is the same though -- that's just too hackish a solution and would create as many problems as it solves. I can already see us trying to troubleshoot why n.d. is randomly not appearing for some citations for someone. Sorry, you'll need to find a different solution for this. I'd agree with bwiernik that having a date appear twice in a citation is probably not a big problem (Chicago Manual purposefully added duplicate years for author-date citations of Newspapers in the last edition, for example, so there's precedent for this)