Yep! In fact, the U.S. Supreme Court decided a landmark copyright case that involved them, although tangentially. In Feist, the Court held that entries in a phone book were not, by themselves, copyrightable. The Court acknowledged that "[f]our of [the listings] were fictitious listings that Rural had inserted into its directory to detect copying," but didn't discuss the importance of those beyond that statement.

https://en.wikipedia.org/wiki/Feist_Publications,_Inc.,_v._R....

https://en.wikisource.org/wiki/Feist_Publications_v._Rural_T...

https://en.wikipedia.org/wiki/Fictitious_entry

Representing information as factual ought to result in it being treated as fact for copyright purposes, even if it's actually fictitious. In addition to opening the publisher up to liability for fraud.