System Information
windows XP/SP3 32bits

Blender Version
Broken: version 2.75 (sub 2), branch b'master', commit date b'2015-07-09' b'21:48', hash b'5513fdc', b'Release'
Worked: (optional)

Short description of error
It is added to all elements when I append a value in list.
Exact steps for others to reproduce the error
Probably I think this to be a problem of python not a problem of blender.
This is because the result that I tried in IDLE of python 2.7/3.4 was the same.
Whether this is specifications of python or is it a bug?

a = [[]]*5
print(a)
a[0].append(1)
print(a)

a = [[1]]*5
print(a)
a[0].append(1)
print(a)