Using Python 3.5+ os.scandir() optimized variant.
Starting.
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*Collecting tree differences
comparing [C:/MY-STUFF/Code/mergeall/test/test1] [C:/MY-STUFF/Code/mergeall/test/test2]
excluding C:/MY-STUFF/Code/mergeall/test/test2\__bkp__
comparing [C:/MY-STUFF/Code/mergeall/test/test1\d1] [C:/MY-STUFF/Code/mergeall/test/test2\d1]
comparing [C:/MY-STUFF/Code/mergeall/test/test1\d3] [C:/MY-STUFF/Code/mergeall/test/test2\d3]
comparing [C:/MY-STUFF/Code/mergeall/test/test1\m2] [C:/MY-STUFF/Code/mergeall/test/test2\m2]
Phase runtime: 0.0007457722872777406
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*Reporting tree differences
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SAMEFILE DIFFERENCES: (name, dirfrom, dirto, why)
**These items will be replaced in dirto by automatic resolution**

[]
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UNIQUE ITEMS IN DIRTO: (names, dirfrom, dirto)
**These items will be deleted from dirto by automatic resolution**

[(['$RECYCLE.BIN', '.Trash-1000', 'Desktop.ini'],
  'C:/MY-STUFF/Code/mergeall/test/test1',
  'C:/MY-STUFF/Code/mergeall/test/test2'),
 (['desktop.ini', 'Thumbs.db'],
  'C:/MY-STUFF/Code/mergeall/test/test1\\d3',
  'C:/MY-STUFF/Code/mergeall/test/test2\\d3')]
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UNIQUE ITEMS IN DIRFROM: (names, dirfrom, dirto)
**These items will be copied over to dirto by automatic resolution**

[(['.DS_Store', '._.TemporaryItems'],
  'C:/MY-STUFF/Code/mergeall/test/test1',
  'C:/MY-STUFF/Code/mergeall/test/test2'),
 (['._.DS_Store', '._someimage.png'],
  'C:/MY-STUFF/Code/mergeall/test/test1\\d1',
  'C:/MY-STUFF/Code/mergeall/test/test2\\d1'),
 (['.DS_Store', '.fseventsd', '.Trashes'],
  'C:/MY-STUFF/Code/mergeall/test/test1\\d3',
  'C:/MY-STUFF/Code/mergeall/test/test2\\d3'),
 (['.DS_Store'],
  'C:/MY-STUFF/Code/mergeall/test/test1\\m2',
  'C:/MY-STUFF/Code/mergeall/test/test2\\m2')]
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MIXED MODE NAMES: (name, dirfrom, dirto)
**These items will be replaced in dirto by automatic resolution**

[]
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*Summary
Compared    => files: 11, folders: 4
Differences => samefile: 0, uniqueto: 5, uniquefrom: 8, mixedmode: 0
Changed:
files   => created: 0, deleted: 0, replaced: 0
folders => created: 0, deleted: 0, replaced: 0
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Finished.