QGIS coordinate precision

The QGIS Delete Duplicate Geometries tool (in the QGIS 2.18's Geoalgorithms, Vector General Tools) is a Python script that operates on the geometry objects exported/exposed by QGIS' Python layer. And underneath this layer is the GEOS layer.

The GEO layer's geometry equality operator accepts a tolerance parameter (in map distance unit) when comparing two geometries. Unfortunately, this tolerance parameter is not exposed by QGIS' Python layer - hence for Delete Duplicate Geometries, two geometries are considered equal if and only if all their XY values are totally equal. E.g., POINT(1.000000 1.000000) is not equal to POINT(1.00000001 1.00000001).