two lost souls swimming in a fishbowl: Pluto and Charon, photographed by Hubble Space Telescope, June 2010.
This study also aimed to image the smaller Plutonian moons Nyx and Hydra. If you look very closely, there appear to be two extremely faint objects that track with Pluto and Charon (at about the 9 and 7 o’clock positions) which might fit the bill.
From Proposal 11556 (Visit 2).
Image credit: NASA/ESA/STScl. Animation: AgeOfDestruction.