Form Update Via Excel is Appending, not Replacing

We have a form in our workflow for budgeting. Users have the option of interacting directly with the form or using a spreadsheet template we provided to update their values. 

There are pre-seeded values in the cube. Users can then make adjustments to the amounts.

When users are updating via the form, we are getting values replaced like we would want.

However, when users interact with the form and update via our provided excel file, the amounts are getting appended to the original value.

We can't seem to locate where this behavior is triggered on upload to form via Excel. Is there something in the VB we need to adjust, or is this a 'standard' behavior. We'd like to let our users simply replace the values. 

Let me know if you need any add'l clarifications.

Regards,
DK