Up to eight MIDI clips can be viewed simultaneously in the Detail View. Note that multi-clip editing will not work if there is an Audio track in between the selected MIDI Clips.
In cases when you have the same notes in multiple MIDI clips, it's possible to see notes from inactive clips by hovering above the Multi-Clip Loop Bars to view the notes of each clip.
Clip Envelopes can only be edited for one clip at a time, not for multiple clips simultaneously.
You can find more information in the Live 10 manual.