Update source file creates a extra response field which is not required

Current behavior:

The user imports a word document containing a set of questions, adds a few more, and then imports the file again using the update source file option once more. The questions are added with an additional response field next to the one that was previously added.

Steps to replicate:
1) Create a new Word document with new questions and import.
2) Respond to every question that is imported and mark it as answered.
3) Next, use the update source file feature to import the document again after adding a few questions.
4) The file has further imports and questions.
5) The question now has two response fields, one of which is filled up and the other is a newly added one.