After taking a look at your XLSForm, it looks like you are encountering this issue due to duplicate values in the 'name' field of your survey sheet (N1, N2, N3, N4).
Please ensure that all values in the name field are unique and that you are not using any reserved words for name's as well (can be checked by looking at the Settings sheet in the XLSForm).
Let me know if changing these issues resolves the error.
I found quite a few reserved keywords being used in the name column in addition to the two you mentioned. I cross checked them using the conditional formatting, duplicate values function and they have all been changed. However, the problem persists and I'm getting the same error message. The updated xls is attached.