Duplicating a layer

When you duplicate a layer, After Effects copies all property keyframes, masks, and effects to the duplicate. The duplicate is added above the original layer and automatically selected. If you want to duplicate a layer without duplicating its keyframes, masks, or effects, add the original source footage file to the composition again.

Note: Track mattes retain their order, on top of the layer when you duplicate or split the layer. (SeeCreating track mattes and traveling mattes.)

To duplicate a layer:

In a Composition or Timeline window, select the layer and choose Edit > Duplicate.