import copy


def merge_id_dicts(dicttuple):
	"""
	Merges two id dictionary (efficiently).

	Args:
		dicttuple (tuple): Tuple of two id dictionaries.

	Returns:
		dict: New merged dictionary
	"""
	dict1, dict2 = dicttuple
	new = copy.deepcopy(dict1)
	for key, value in dict2.items():
		new.setdefault(key, []).extend(value)
	return new