While the 2 column CSV format allows you to add only one question and answer per intent, you can specify multiple training phrases and multiple responses per intent using the 4 column format. You can download a sample 4 column CSV file at the bottom of this article.
The following image shows an example of the 4 column format.
The CSV file should have exactly 4 columns, and the column names are mandatory AND case sensitive:
I recommend downloading a sample CSV file and modifying the contents without changing the header row.
Use the same IntentID to group all the information belonging to a single intent
The IntentID should be a number. However, the IntentID is only used for grouping all the information and you can use whatever number you want. It doesn't even have to be in order in the CSV file.
The second column is the IntentName
You cannot use the forward-slash character (/) in the IntentName since it interferes with how the file system generates your ZIP file.
Specify multiple training phrases for a single intent in the Query column
When you add more training phrases in the Query column (remember to use the same IntentID), these will be added as unique training phrases into your Dialogflow intent.
Specify multiple responses for a single intent in the Response column
Remember that when you have multiple responses in a single response block in Dialogflow, it randomly selects only one of the responses and doesn't show all the responses in sequence. For some reason, people always seem to be confused by this in Dialogflow.
How it gets translated
Now let us consider what the agent looks like for the CSV file you see above.
As you can see, while the IntentID is useful to group the information for an intent, it doesn't actually show up in the final agent ZIP file.