what is the __dict__ object?

[snippsat]

i think if id() function gives the same address for two objects,they must be the same object.

Use code tags.
There not same object,but something strange happens when making into a tuple object.

>>> class A:
...     pass
...
... class B:
...     pass

>>> id(A.__dict__)
62085776

>>> id(B.__dict__)
62373680

So when use , between object,Python is making a tuple.
This is when the somewhat strange execution happens.

>>> id(A.__dict__), id(B.__dict__)
(136355152, 136355152)

It look like when using special method in tuple creation it call same object.

>>> a = 'foo'
>>> b = 'bar'

>>> id(a)
128252192
>>> id(b)
61876128

>>> id(a), id(b)
(128252192, 61876128)

Using .__add__ the same happens.

>>> id(a.__add__), id(b.__add__)
(62304752, 62304752) 

Nothing to worry about,
this is some internal stuff with id() and special method in tuple creation.