Tricky way to copy/paste layer from one document to another in Photoshop CS5

When you want to copy and paste layer from one document to another in Photoshop, use this trick. Let's say you made a sign and want to insert it in another document, you need to have both documents open in Photoshop.

Right-click (Opt-click) the layer that you want to copy and paste (duplicate to another document) and choose Duplicate Layer ...

In the Duplicate Layer dialog box that opens, click triangle on right side of Document: and choose name of the document in which you want to paste the copied Layer, then click OK.

Copied layer will appear in exactly the same position relative to the image (if you have images of the same dimensions as in this case). This is copied and pasted layer so you have exactly the same layer in both documents.

Reference:
Photoshop / Layer basics

Product used in this tutorial: Adobe Photoshop CS5