No, PTO does not have the functionality to download data for offline backup, export, or conversion.  The only type of backup you can have, as George pointed out, is PDF files of your returns.  Intuit does, on the other hand, back up your data in the cloud and have multiple redundancy as you would expect.

Since returns you complete will not remain static (regardless of the Status you may select) and will be altered by new releases for tax logic updates as well as for inadvertent changes made by users who access the returns, it is advisable that you ALWAYS download PDF of each return you complete as a record of the actual return that was filed.