Date in CMS map citation

I input map information into Zotero

Item Type: Map
Title: California: Yosemite Quadrangle
Cartographer: U.S. Geological Survey
Type: 30-minute series quadrangle
Scale: 1:125,000
Date 1909
Archive: Historic Topographic Map Collection

and the CMS 17th footnote was output like so:

U.S. Geological Survey, California: Yosemite Quadrangle, 1909, 30-minute series quadrangle, 1:125,000, 1909, Historic Topographic Map Collection,

Why is the date appearing twice?
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