It means the same, but the connotation is slightly different. Your phrasing puts the emphasis on the end result (the data), while “If in doubt, leave it out.” puts the emphasis on the editor’s thought process (“doubt”) and actions leading up to the end result (“leave it out”). (I also get the feeling that many (esp. new) editors feel like they have to fill out. every. single. field. So telling them that they can “leave it out” also validates the action of not filling in a given field.)
In the end, it’s the same thing, just from slightly different angles.