Duplicate keyframes (copy/paste) across layers without duplicating layers

Hello,

I'm having a problem that I hope has an easy fix. I am able to copy and paste one keyframe from one layer at a time by selecting the keyframe, moving the time indicator and pasting. No new layer created.

However, this is very inefficient and I would like to select multiple keyframes across many layers, move the time indicator, and paste to duplicate an entire set of keyframes. When I do this, the graphic layer I'm working on is duplicated rather than the just the keyframe.

How can I avoid this?