To write Error message grouped by a common field attribute value and check another field value is matching for that same group instance using arcpy

The name of my layer is "spat_join_output". So I have a field named ‘label’ and another two fields ‘end_point_x’ and ‘end_point_y’ for the same label values i want to check if the end_point_x and end_point_y values are same , i want to drop an error message in another field named as "Error".

I have my code as :-

array_fibre = arcpy.da.FeatureClassToNumPyArray("spat_join_output", ["label", "end_point_x", "end_point_y", "OBJECTID"], skip_nulls = True)
        # arcpy.AddMessage(array_fibre)
        for data in array_fibre:
            arcpy.AddMessage(str(data))

    if arcpy.Exists("spat_join_output"):
        arcpy.AddField_management("spat_join_output", "Error", "Text", 100)

    with arcpy.da.UpdateCursor("spat_join_output", ["label", "end_point_x", "end_point_y", "Error"]) as cursor:
        for row in cursor:
            if row[0] != None and row[1] != None and row[2] != None:
                data = self.find_endpoints(array_fibre, row[0])
                if len(data) > 0:
                    arcpy.AddMessage(data[0])
                    
        del cursor

I am trying to build a function for this, using an array method,

def find_endpoints(self, array, id):
    count = 0
    array_id = []
    end_point_X_y = []
    array_label = []
    if len(array) > 0:
        array_count = 0
        for data in array:
            if len(array_label) == 0 and id in data[0]:
                array_label.append(data[0])
            elif len(array_label) > 0 and id in data[0]:
                array_label.append(data[0])

This is how my array looks:-

(‘CAS/C003’, ‘-877644.7019000016’, ‘6893765.545000002’, 2)
(‘CAS/C003’, ‘-877939.7175000012’, ‘6893358.312799998’, 3)
(‘CAS/C003’, ‘-877244.6374999993’, ‘6893426.772500001’, 4)

import arcpy

fc = r'C:Default.gdbspat_join_output'
fields = ['Label','end_point_x','end_point_y','Error']

data = set()

with arcpy.da.UpdateCursor(fc, fields) as cursor:
    for row in cursor:
        key = ' '.join([str(i) for i in row[:-1]]) #'CAS/C003 -877244.6374999993 6893426.772500001'
        if key in data:
            row[-1] = 'Duplicate found'
            cursor.updateRow(row)
        data.add(key)