I found your page containing the form.
The problem is that you have added a server connect component on the page, which runs the same server action as your form runs:
So on page load it runs the insert action, which of course inserts a blank record.
Then on form submit the insert action runs again and inserts the data.
You should not the server connect component on that page - the insert must only run through the form.
And also - for insert record action, you should not use the “populate” option of the form generator. It’s only needed for an update record form, where you need to see the record which you are updating.