Variable CFF2 fails due to OTF interpolatable drops duplicate point if starting point is in inner side

[NightFurySL2001]

Source file with error: TestDoublePoint.zip

fontmake 3.10.1, fonttools v4.58.4, ufo2ft 3.5.0

If a starting point is set at this specific corner with another point duplicating in the same location, when building variable-cff2 or otf-interpolatable, the point will be dropped.

fontmake .\TestDoublePoint.designspace -o variable-cff2 raises:

INFO:fontmake.font_project:Loading 2 DesignSpace source UFOs
INFO:fontmake.font_project:Building variable fonts variable_otf\TestDoublePoint-VF.otf
INFO:ufo2ft:Features are compatible across masters; building later
INFO:ufo2ft:Pre-processing glyphs
INFO:ufo2ft.filters:Running interpolatable DecomposeComponentsIFilter
INFO:ufo2ft:Building OpenType tables for TestDoublePoint-Regular
INFO:ufo2ft:Building OpenType tables for Unnamed-Regular
INFO:ufo2ft:Building variable font: TestDoublePoint-VF
INFO:fontTools.varLib:Axes:
[{'axisLabels': [],
  'axisOrdering': None,
  'default': 1000.0,
  'hidden': False,
  'labelNames': {'en': 'Weight'},
  'map': [(1.0, 1.0), (400.0, 400.0), (1000.0, 1000.0)],
  'maximum': 1000.0,
  'minimum': 1.0,
  'name': 'weight',
  'tag': 'wght'}]
INFO:fontTools.varLib:Internal master locations:
[{'weight': 1000.0}, {'weight': 1.0}]
INFO:fontTools.varLib:Internal axis supports:
{'weight': [1.0, 1000.0, 1000.0]}
INFO:fontTools.varLib:Normalized master locations:
[{'weight': 0.0}, {'weight': -1.0}]
INFO:fontTools.varLib:Index of base master: 0
INFO:fontTools.varLib:Building variable font
INFO:fontTools.varLib:Loading master fonts
INFO:fontTools.varLib:Generating fvar
INFO:fontTools.varLib:Building variations tables
INFO:fontTools.varLib:Generating avar
INFO:fontTools.varLib:No need for avar
INFO:fontTools.varLib:Generating MVAR
INFO:fontTools.varLib:Generating HVAR
fontmake: Error: In 'TestDoublePoint.designspace': Generating fonts from Designspace failed: Glyph 'test': 'rlineto' at point index 24 in master index 1 differs from the default font point type 'rmoveto'

going through fontmake .\TestDoublePoint.designspace -o otf-interpolatable and then run AFDKO buildcff2vf -d ./master_otf_interpolatable/TestDoublePoint.designspace -c raise the same error too:

Reading source fonts...
Checking outline compatibility in source fonts...
Traceback (most recent call last):
  File "<frozen runpy>", line 198, in _run_module_as_main
  File "<frozen runpy>", line 88, in _run_code
  File "C:\Python311\Scripts\buildcff2vf.exe\__main__.py", line 7, in <module>
  File "C:\Python311\Lib\site-packages\afdko\buildcff2vf.py", line 564, in main
    do_compatibility(vf, font_list, ds_data.base_idx)
  File "C:\Python311\Lib\site-packages\afdko\buildcff2vf.py", line 332, in do_compatibility
    region_charstring.draw(compat_pen)
  File "C:\Python311\Lib\site-packages\fontTools\misc\psCharStrings.py", line 1168, in draw
    extractor.execute(self)
  File "C:\Python311\Lib\site-packages\fontTools\misc\psCharStrings.py", line 636, in execute
    super().execute(charString)
  File "C:\Python311\Lib\site-packages\fontTools\misc\psCharStrings.py", line 360, in execute
    rv = handler(index)
         ^^^^^^^^^^^^^^
  File "C:\Python311\Lib\site-packages\fontTools\misc\psCharStrings.py", line 727, in op_rlineto
    self.rLineTo(point)
  File "C:\Python311\Lib\site-packages\fontTools\misc\psCharStrings.py", line 654, in rLineTo
    self.pen.lineTo(self._nextPoint(point))
  File "C:\Python311\Lib\site-packages\fontTools\pens\basePen.py", line 328, in lineTo
    self._lineTo(pt)
  File "C:\Python311\Lib\site-packages\fontTools\varLib\cff.py", line 538, in _lineTo
    self.add_point("rlineto", pt_coords)
  File "C:\Python311\Lib\site-packages\afdko\buildcff2vf.py", line 134, in add_point
    raise VarLibCFFPointTypeMergeError(
fontTools.varLib.errors.VarLibCFFPointTypeMergeError: Glyph 'test': 'rlineto' at point index 24 in master index 1 differs from the default font point type 'rmoveto'

the point is dropped in EL OTF.