remove_bezier_doubles.py

import bpy

''' selects an set which is the same as a direct previous set, removed them at the end '''

import mathutils
from mathutils import Vector

def check_similarity(old_set, new_set, distance=0.0001):
    if None in old_set:
        return False
    else:
        for co_old, co_new in zip(old_set, new_set):
            if (co_old-co_new).length < distance:
                continue
            else:
                return False
    
    # reaches here only if all old/new coordinates where closer than 'distance'.
    return True

bpy.ops.curve.select_all(action='DESELECT')

obj = bpy.context.active_object
splines = obj.data.splines

old_set = None, None, None

# A Curve data-type can hold multiple disjoint curves/splines
for idx, spline in enumerate(splines):
    for cidx, bp in enumerate(spline.bezier_points):
        new_set = (bp.co, bp.handle_left, bp.handle_right)
        if check_similarity(old_set, new_set):
            print(idx, cidx)
            bp.select_control_point = True
        else:
            old_set = new_set
            
bpy.ops.curve.delete(type='VERT')