A layer can have two names , the one it comes in with, and the one you give it. Why is this useful? It all boils down to you keeping control. Perhaps you have added a footage item five times into your composition. If every layer was called Shot 1, you might get confused . We would.
Highlight the layer to rename it.
Press Return (Enter).
Type the new name.
Press Return (Enter) to apply the name, or click on another layer.
If you'd like to toggle between all of the Source Names and the Layer Names, click the name field at the top of the timeline.