What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
At JotForm, we want to make sure that you’re getting the online form builder help that you need. Our friendly customer support team is available 24/7.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
Yes, you can integrate your JotForm form to Google spreadsheet by following this guide: https://www.jotform.com/help/228-How-to-Integrate-Form-with-Google-Spreadsheet. It should automatically load all the existing submission of your form in the spreadsheet, now every time there's a new submission, it will automatically be added in the spreadsheet.
I hope that helps.
How does it handle duplicate data?
It will export each submission from your submissions page into a separate row in the integrated Google Spreadsheet. In addition to integrating your form with Google Spreadsheet, you can also manually export your submissions into Excel format at any time:
The exporting process, either with Excel fiels or with Google Spreadsheets, doesn't add any additional handling / processing of possible duplicated data.
If you have duplicated submissions on your form's submissions page, you will have duplicated entries / rows in the Google Spreadsheet and any exported Excel files. Each submissions is in its own row in the spreadsheet.
Please let us know if you need further assistance or clarifications, and we will be happy to help.