"Abuelos incognitos"?

I recently ran across a church baptismal record on familysearch.org that stated "abuelos incognitos". This doesn't seem to me that the grandparents were unknown but for some reason are unlisted.
Has anyone run across this before? Why would the grandparents not be named? Any ideas?
Thanks in advance for any insight.

Cindy (Barela) Fahrbach
email: genie_research@hotmail.com
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Researching: Banegas, Barela, Cutler,
De La O, Fahrbach, Jimenez, Keller,
May, Navarro, Starnes, Utley, Ybarra
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