Issue in CRM 2015 Update 1 Online:

When clicking Get Data template or trying to get data from Export to excel using Static or dynamic worksheet, users are reporting the following error:

Resolution for Data template:

Use XRM Toolbox in case of Data template to find duplicate column names using Meta Data document generator and rename duplicate display names (which are on form). Data template file is generated using form fields.

Resolution for Export to excel using Static worksheet or Dynamic Worksheet:

Remove duplicate column names from the view you are using (Do not include (base) fields for Currency fields)

Hope it helps and Happy CRMing!