How to Duplicate a Layer,Merge two photos in Photoshop

Step 1:

Open thr First Photo ----Here i am opening "Aishwarya's Photo"

Step 2:

Open the Second Photo---Here my second pic is of "Kareena's Photo"

Step 3:

In the Second (kareena's Pic), In the Layers window at the right bottom of the screen. Right click on the layer and Select Duplicate layer Option

Step 4:

In the Duplicate Layer Window, in the Destination document select the first Photo on to which you would like to duplicate this photo, here it is "Aishwarya"

Step 5:

Then you will see the Second Pic " kareena" on to the first pic "Aishwarya". Click Ctrl+T to adjust the angle,size of the pic you have selected and adjust both the pictures by selecting the respective layers..

Video:

Note: In order to make the merging more lively you can extract the particular portion of the pic and then duplicate, so as to make it more original when required.

To Extract the particular portion, Follow the Following steps

Step 1:
Go to Filter>> Extract ,

Step 2:
Select the Edge Highlighter tool and mark the edges of the area that you want to retain

Step 3:
Select the paint bucket tool and fill the area that you want to retain with the paint and click ok. and then Duplicate the layer on to first pic for perfection

Final Pic would be like this