WMG / Star Trek: Deep Space Nine S03 E05 "Second Skin"

The preserved body Entek shows Kira is a genuine body...

...but it's the genuine body of the real Iliana Ghemor. She died on Bajor still believing she was a freedom fighter who'd lost her parents to the Cardassians, and Entek and the Obsidian Order chose to a. retrieve her body before anyone could discover she wasn't really Bajoran (which would have blown their entire plan of disguising Cardassians as Bajorans in order to infiltrate the resistance) and b. preserve it as a possible future weapon against Legate Ghemor, who they may have already been suspicious of. Finding a Bajoran woman who looked almost exactly like the disguised Iliana was a piece of serendipity that they were quick to capitalize on, but they had a dozen other plans to draw him out, and a hundred more that didn't necessarily involve Iliana's corpse.