if you are on MacOS, merging hot and memory cues and set them both identical is one of the functions of the Rekordbox Cue and Key Tool
And the good news is that ReCK now works with Rekordbox 6.
Convert Mixed in Key cues to Rekordbox and more: Rekordbox Cue and Key Tool (ReCK) [MacOS]
Rekordbox 6 and Mixed in Key cues: the Rekordbox Cue and Key Tool (ReCK)