can compile function have a bug?

[ygao]

>>> compile('U"中"','c:/test','single')
<code object ? at 00F06B60, file "c:/test", line 1>
>>> d=compile('U"中"','c:/test','single')
>>> d
<code object ? at 00F06BA0, file "c:/test", line 1>
>>> exec(d)
u'\xd6\xd0'
>>> U"中"
u'\u4e2d'
>>>

why is the result different?
a bug or another reason?