How come I see scenes from a previous video call in other video calls?

Q: Hi,

In Skype, is it normal to have earlier scenes of a video call to appear twice for a second during the later part of the same live streaming webcam video call.

Is this as a result of third party recording the video call? Or is it due to some network issues or other technical issues? I am worried if there is any hacking going on. Technical geniuses please help with this query.