Analysis of information sources in references of the Wikipedia article "Deep Impact (spacecraft)" in English language version.
The Stardust spacecraft, which had been recycled for a second mission called Stardust-NExT, flew by comet Tempel 1, marking the first time a comet had been visited twice by any spacecraft.
Deep Impact's possible January 4, 2020 flyby would be a nice one, at a close-approach distance of around 200 kilometers and a relative velocity of 7 kilometers per second. That's both closer and slower than the Hartley 2 flyby (which was at 700 kilometers and 12 kilometers per second).