Clone can duplicate an entire set of keyframes across multiple properties, and across multiple layers. Typically, After Effects can't understand keyframe copy/pasting over multiple layers and will duplicate the layer. So Clone is a fantastic tool to make this process more automated.
Setup
Select any amount of keyframes
move the CTI to a location on the Timeline
set the Clone options and Run Clone
the keyframe set will be pasted to CTI position
Options
When running Clone there are a couple different modes you can select to Clone the keyframes.
Standard
This option will simply paste the keyframe set to the CTI position
Reverse
Will reverse each set of keyframes independently on each property.
Mirror
Will flip the entire keyframe group order together "reversed as a group"
After Effects