How can i copy the bigym env for planning?

[W-Zhi-Chao]

I'm trying to use copy.deepcopy(env) to create a copy of current env for planning, but i get the following error. Any tips for creating an env copy?
tmp_demo_env = copy.deepcopy(demo_env)
File "/opt/conda/envs/robobase/lib/python3.10/copy.py", line 172, in deepcopy
y = _reconstruct(x, memo, *rv)
File "/opt/conda/envs/robobase/lib/python3.10/copy.py", line 271, in _reconstruct
state = deepcopy(state, memo)
File "/opt/conda/envs/robobase/lib/python3.10/copy.py", line 146, in deepcopy
y = copier(x, memo)
File "/opt/conda/envs/robobase/lib/python3.10/copy.py", line 231, in _deepcopy_dict
y[deepcopy(key, memo)] = deepcopy(value, memo)
File "/opt/conda/envs/robobase/lib/python3.10/copy.py", line 172, in deepcopy
y = _reconstruct(x, memo, *rv)
File "/opt/conda/envs/robobase/lib/python3.10/copy.py", line 271, in _reconstruct
state = deepcopy(state, memo)
File "/opt/conda/envs/robobase/lib/python3.10/copy.py", line 146, in deepcopy
y = copier(x, memo)
File "/opt/conda/envs/robobase/lib/python3.10/copy.py", line 231, in _deepcopy_dict
y[deepcopy(key, memo)] = deepcopy(value, memo)
File "/opt/conda/envs/robobase/lib/python3.10/copy.py", line 172, in deepcopy
y = _reconstruct(x, memo, *rv)
File "/opt/conda/envs/robobase/lib/python3.10/copy.py", line 271, in _reconstruct
state = deepcopy(state, memo)
File "/opt/conda/envs/robobase/lib/python3.10/copy.py", line 146, in deepcopy
y = copier(x, memo)
File "/opt/conda/envs/robobase/lib/python3.10/copy.py", line 231, in _deepcopy_dict
y[deepcopy(key, memo)] = deepcopy(value, memo)
File "/opt/conda/envs/robobase/lib/python3.10/copy.py", line 172, in deepcopy
y = _reconstruct(x, memo, *rv)
File "/opt/conda/envs/robobase/lib/python3.10/copy.py", line 271, in _reconstruct
state = deepcopy(state, memo)
File "/opt/conda/envs/robobase/lib/python3.10/copy.py", line 146, in deepcopy
y = copier(x, memo)
File "/opt/conda/envs/robobase/lib/python3.10/copy.py", line 231, in _deepcopy_dict
y[deepcopy(key, memo)] = deepcopy(value, memo)
File "/opt/conda/envs/robobase/lib/python3.10/copy.py", line 153, in deepcopy
y = copier(memo)
File "/opt/conda/envs/robobase/lib/python3.10/site-packages/dm_control/mjcf/element.py", line 1298, in deepcopy
return self.copy()
File "/opt/conda/envs/robobase/lib/python3.10/site-packages/dm_control/mjcf/element.py", line 1294, in copy
new_model.include_copy(self)
File "/opt/conda/envs/robobase/lib/python3.10/site-packages/dm_control/mjcf/element.py", line 1244, in include_copy
other_copier = copier.Copier(other)
File "/opt/conda/envs/robobase/lib/python3.10/site-packages/dm_control/mjcf/copier.py", line 27, in init
raise NotImplementedError('Cannot copy from elements with attachments')
NotImplementedError: Cannot copy from elements with attachments