co_consts are merged already, but I forget about code attributes other than co_consts.
Duplication ratio is vary by code style, but in case of logging, we can reduce 25% of them.

```
>>> data = open('Lib/logging/__pycache__/__init__.python-310.pyc', 'rb').read()
>>> import marshal
>>> x = []
>>> def walk(c):
...     x.append(c.co_code)
...     x.append(c.co_lnotab)
...     for cc in c.co_consts:
...         if hasattr(cc, 'co_code'):
...             walk(cc)
...
>>> code = marshal.loads(data[16:])
>>> walk(code)
>>> len(x)
336
>>> len(set(x))
249
>>> 249/336
0.7410714285714286
```