In Blender 2.8 you can create a video clone, i.e. you can appear twice in the same video. Its not too difficult but has many steps to ensure the quality is good. The first step of course is to get some video footage with you in the two positions that you want to keep. It is important that the camera is in a fixed position so nothing is moving (this can be overcome but we are doing a simple clone). Once you have your footage you will need to open the compositor. It should look something like this.

Each of these nodes will be explained below.

The first image node will have one version of the video in it. The setting are important to have it only show the portion of the video that you want from this node. The number of frames and offset should be used to get the right portion of the video to display. – When playing the video in the compositor you may not see the animation as it takes time to render.

The second image node will be set to show the part of the video with your clone in it.

The first image node should be connect to

an Alpha Over node in the top image slot. The second image node should be connected into the bottom image slot. The output from the Alpha Over should be connected to the viewer node and the composite node as shown above.

In the image editor you should create a mask

Just mask off the half of the video that you is in the second image node.

Now create a mask node.

select the mask that you created in the image editor. Connect the mask output to the mask input of a dilate/erode node.

Connect the output of the Dilate/Erode node to the fac input on the alpha over node. If you adjust the image frames and offsets correctly you should now have a composite video. You will need to change the render output to composite and uncheck sequencer. Try rendering and see what you have.