class C1 (object):
    def __init__ (self, title, plus = True):
        self.title = title
        self.plus = plus
        self.acc = 0

    def add (self, x):
        if self.plus:
            self.acc += x
        else:
            self.acc -= x

    def __str__ (self):
        return "C1(%s,%g)" % (self.title,self.acc)

class C2 (object):
    def __init__ (self, title):
        self.title = title
        self.all = list()

    def add (self, x, pos = None):
        if pos:
            self.all.append(x)
        else:
            self.all.insert(pos,x)

    def __str__ (self):
        return "C2(%s,%s)" % (self.title,self.all)

import random
class RandomPair (object):
    def __init__ (self, klass, title, **kwargs):
        self.objects = [klass(title + "#" + str(i), kwargs) for i in range(2)]

    def add (self, *args, **kwargs):
        print args,kwargs
        self.objects[random.randint(0,1)].add(args,kwargs)

    def __str__ (self):
        return "n".join([str(o) for o in self.objects])

rp1 = RandomPair(C1,"test")
rp1.add(1)
rp1.add(2)
rp2 = RandomPair(C2,"test")
rp2.add(1)
rp2.add(2, pos=0)

TypeError: add() got multiple values for keyword argument 'self'

self.objects[random.randint(0,1)].add(*args, **kwargs)