Why does clicking the add button on the expense sheet creates 3 duplicate rows?

In an expense sheet the '+' button beside each row helps add more rows quickly and , enables a user to create a duplicate of that row below it with the same entries. The advantage over this is as follows,

• This useful where the user has to create multiple entries that are nearly identical entries.
• The user only has to edit the changes required, rather than creating a new row and entering the details.