ODS file corrupts when I duplicate a sheet

[ItaloCunhaBueno]

Here's my code example

import ezodf as ods


file = r'example_file.ods'
for x in range(2, 6):
    print(x)
    ODS = ods.opendoc(file)
    per1 = ODS.sheets['perimetro_1'] #the example file has a sheet called 'perimetro_1'
    duplicate = per1.copy(newname='perimetro_{0}'.format(x))
    ODS.sheets += duplicate
    ODS.save()

when trying to duplicate for the second time, this error occurs:

Traceback (most recent call last):
  File "e:\Trabalho\Repos\Geoja\Gra\SGT\teste.py", line 7, in <module>
    ODS = ods.opendoc(file)
  File "C:\Program Files\Python37\lib\site-packages\ezodf\document.py", line 54, in opendoc
    return PackagedDocument(filemanager=fm, mimetype=mime_type)
  File "C:\Program Files\Python37\lib\site-packages\ezodf\document.py", line 226, in __init__
    self.content = OfficeDocumentContent(mimetype, fm.get_xml_element('content.xml'))
  File "C:\Program Files\Python37\lib\site-packages\ezodf\filemanager.py", line 136, in get_xml_element
    return etree.XML(filecontent)
  File "src\lxml\etree.pyx", line 3216, in lxml.etree.XML
  File "src\lxml\parser.pxi", line 1896, in lxml.etree._parseMemoryDocument
  File "src\lxml\parser.pxi", line 1784, in lxml.etree._parseDoc
  File "src\lxml\parser.pxi", line 1141, in lxml.etree._BaseParser._parseDoc
  File "src\lxml\parser.pxi", line 615, in lxml.etree._ParserContext._handleParseResultDoc
  File "src\lxml\parser.pxi", line 725, in lxml.etree._handleParseResult
  File "src\lxml\parser.pxi", line 654, in lxml.etree._raiseParseError
  File "<string>", line 2
lxml.etree.XMLSyntaxError: ID control9 already defined, line 2, column 1190729