Even for long-time Mac users, it can be challenging to identify the differences between Save, Save As, and Duplicate. Save is seemingly straightforward, but not necessarily so—a lot happens behind the scenes for every save in Pages, Keynote, and Numbers, among other apps from Apple and those that adapt the Save/Duplicate/Save As approach.
For apps that support storing versions of files, each Save not only takes the current changes stored temporarily for an active document and writes them to a file on a volume, but also may create an archived version of the file’s previous state. Apple says that a version is stored each hour and then also for any time major changes are made in a document, without being too specific about how significant those changes are.
You can manage the version history through File > Revert To > Browse All Versions, as I wrote about in a recent column describing how to purge older versions.
By default, the File menu shows Duplicate below the Save item. Choosing File > Duplicate creates a copy of the current state of the file, including unsaved changes. The copy is a separate document that has as its name the original file’s title plus the word “Copy,” and the title is highlighted.
The file is stored in the same location as the original once the title is edited; in the meantime, it’s stored temporarily in iCloud Drive, typically in the location devoted to the app you’re using, like Pages.
Duplicate detaches itself from old versions, so you can’t revert to earlier forms of the original file, and starts its own version history. However, you can always open the original file—so long as you didn’t delete it—and review its version history.
Trying to close the duplicate without saving brings up a Save dialog that asks if you want to keep the document and offers Delete Copy, Cancel, and Save as options.
Hold down the Option key and File > Duplicate changes to the previous and long-running menu item Save As. Select that option, and a Save As dialog appears allowing you to choose a name and destination for the file.
Save As differs in three ways from Duplicate:
The original file isn’t left open, but the current window adopts a new file name or location or both.
The Save As dialog lets you choose any destination for the file before editing it.
If the document contains unsaved changes, the app includes a checkbox in the Save As dialog that reads “Keep changes in original document.” If checked, the app performs a Save operation in the original file, then saves the new version and leaves that as the only open, active window.
However, like Duplicate, Save As trims the version history: the new file has a fresh start.
This Mac 911 article is in response to a suggestion by Macworld reader Aaron.
Ask Mac 911
We’ve compiled a list of the questions we get asked most frequently along with answers and links to columns: read our super FAQ to see if your question is covered. If not, we’re always looking for new problems to solve! Email yours to firstname.lastname@example.org including screen captures as appropriate, and whether you want your full name used. Not every question will be answered, we don’t reply to email, and we cannot provide direct troubleshooting advice.