Nikon D780 DSLR Camera (Body Only) - Manual (Page 430)

384 Playback
A Calendar Playback
During calendar playback, you can delete all photographs taken on a
selected date by highlighting the date in the date list and pressing the
O
( Q ) button.
A Deleting Copies
If the picture selected in the playback display
when the
O ( Q ) button is pressed was
recorded with two memory cards inserted and
[
Backup ] or [ RAW Slot 1 - JPEG Slot 2 ]
selected for [ Role played by card in Slot 2 ],
you will be prompted to choose whether to
delete both copies or only the copy on the card
in the current slot (
0 281).