INSERT INTO ON DUPLICATE KEY UPDATE Not working! Inserting new rows instead?

Question

I have a dataframe, df, I want to update on duplicate keys but new rows are appearing instead? I'm using the code below. Why is this happening? The Mysql 'table' structure may be impacting this as it has two primary keys? ID Column is a Primary Key, and IDT Column is a Primary Key, Unique & Auto Increment Assigned. Any ideas?

df = df[['ID', 'aa', 'bb', 'cc']]
df = df.values.tolist()
query = """INSERT INTO table(ID, aa, bb, cc)
           VALUES (%s, %s, %s, %s)
           ON DUPLICATE KEY UPDATE
               aa = VALUES(aa),
               bb = VALUES(bb),
               cc = VALUES(cc);"""
cursor.executemany(query, df)