When copying and pasting features in ArcMap, the newly created features will automatically have their attributes added to the layer's table. The pasted features will have coincident geometries with the features that were copied.
This method of copying and pasting records is only valid for attribute tables of layers. It will not work for tables that have no associated features or tables in a database.
The new records are added at the end of the table.
To undo any edit to a table, click the Undo button . You can undo any edits you've made within the current edit session.