I ran into a similar problem with the Artwork Item type, which I used for a photograph.

Title: John McClaren and John Muir at McCloud River, California
Artist: Herrin, William F.
Date [ca. August 1914]
Archive: John Muir papers....
Location in Archive: MSS048.f26-1447.tif

and the footnote was output with two dates. It also ignores the [ca. ], which is important to include in this citation.

William F. Herrin, John McClaren and John Muir at McCloud River, California, August 1914, August 1914, MSS048.f26-1447.tif, John Muir Papers, Mss48, Holt-Atherton Department of Special Collections, University of the Pacific Library, https://scholarlycommons.pacific.edu/jmp/98/.

Was this looked into?

You can't get Zotero to display ca. in dates, though, sorry.

ah yes, apologies, just doesn't work via the regular data field. We can take a look.

The date is still showing up twice in the map footnote as well.

Yes, they are still planned, but @adamsmith appears to not have had a chance yet.

The problem with the date appearing twice in citations for item types Map and Artwork has not been fixed. Of course, these citations could be edited, but that would break the links to the Zotero library, which I am trying to avoid.

I am also experience the same problem with artwork date duplication. How do I fix this? I understand that I can manually edit the footnote, but this breaks the link with Zotero.

I am not using "ca." just simply trying to cite artwork and the date (in my case just the year) is appearing twice in the footnote.

Zotero version: 5.0.82
Microsoft Word for Mac version: 2019 / 16.34
Style: CMS 17th full note

No, sorry, this was fixed but I introduced a regression some months later.

If you're in a rush, you can use this style:
https://raw.githubusercontent.com/citation-style-language/styles/4f1eb525b73820125762a5a763d42961fd5534e3/chicago-fullnote-bibliography.csl (right-click --> save link as and then install using double-click) but obviously we'll fix this as soon as possible

see above, same explanation