Is it possible to join them instead? If you are v10.2 and above, you create join on a calculated field. In your case, you may join them on dates.
Hi Tushar, thank you for your prompt reply.
I should've specified, I'm on version 9.1
Have you considered doing a union of the two source based on the date column. This will allow you to have the both the dates in one columns and you would also get all the dates from both the sources.After doing so you can pull this new date column in you x axis to get all the dates in a single axis.
However before performing the union check the structure of the table and note the relevant columns.
You can refer to the below link for your reference,
I hope this is what you were looking for