Issue #404 wontfix
You should be able to rename a sheet to its own existing name, but currently you can't:
>>> wb = openpyxl.Workbook() >>> ws = wb.active >>> ws.title 'Sheet' >>> ws.title = 'Sheet' >>> ws.title 'Sheet1'
I believe the straightforward and proper way to fix this is simply to add a test at the beginning of the title setter:
if value == self._title: return