diff --git a/test/test_libs.py b/test/test_libs.py
index de3e8c665c4..51f3a5745cb 100644
--- a/test/test_libs.py
+++ b/test/test_libs.py
@@ -513,6 +513,17 @@ def test_brax_grad(self, envname, batch_size):
         env.close()
         del env
 
+    @pytest.mark.parametrize("batch_size", [(), (5,), (5, 4)])
+    def test_brax_parallel(self, envname, batch_size, n=1):
+        def make_brax():
+            env = BraxEnv(envname, batch_size=batch_size, requires_grad=False)
+            env.set_seed(1)
+            return env
+
+        env = ParallelEnv(n, make_brax)
+        tensordict = env.rollout(3)
+        assert tensordict.shape == torch.Size([n, *batch_size, 3])
+
 
 if __name__ == "__main__":
     args, unknown = argparse.ArgumentParser().parse_known_args()
diff --git a/torchrl/envs/libs/brax.py b/torchrl/envs/libs/brax.py
index 7d768f34cd3..a1fbca2079b 100644
--- a/torchrl/envs/libs/brax.py
+++ b/torchrl/envs/libs/brax.py
@@ -151,7 +151,7 @@ def _set_seed(self, seed: int):
             raise Exception("Brax requires an integer seed.")
         self._key = jax.random.PRNGKey(seed)
 
-    def _reset(self, tensordict: TensorDictBase, **kwargs) -> TensorDictBase:
+    def _reset(self, tensordict: TensorDictBase = None, **kwargs) -> TensorDictBase:
 
         # generate random keys
         self._key, *keys = jax.random.split(self._key, 1 + self.numel())
@@ -164,11 +164,13 @@ def _reset(self, tensordict: TensorDictBase, **kwargs) -> TensorDictBase:
         state = _object_to_tensordict(state, self.device, self.batch_size)
 
         # build result
+        reward = state.get("reward").view(*self.batch_size, *self.reward_spec.shape)
+        done = state.get("done").bool().view(*self.batch_size, *self.reward_spec.shape)
         tensordict_out = TensorDict(
             source={
                 "observation": state.get("obs"),
-                "reward": state.get("reward"),
-                "done": state.get("done").bool(),
+                "reward": reward,
+                "done": done,
                 "state": state,
             },
             batch_size=self.batch_size,
@@ -195,11 +197,19 @@ def _step_without_grad(self, tensordict: TensorDictBase):
         next_state = _object_to_tensordict(next_state, self.device, self.batch_size)
 
         # build result
+        reward = next_state.get("reward").view(
+            *self.batch_size, *self.reward_spec.shape
+        )
+        done = (
+            next_state.get("done")
+            .bool()
+            .view(*self.batch_size, *self.reward_spec.shape)
+        )
         tensordict_out = TensorDict(
             source={
                 "observation": next_state.get("obs"),
-                "reward": next_state.get("reward"),
-                "done": next_state.get("done").bool(),
+                "reward": reward,
+                "done": done,
                 "state": next_state,
             },
             batch_size=self.batch_size,
@@ -222,12 +232,18 @@ def _step_with_grad(self, tensordict: TensorDictBase):
         )
 
         # extract done values
-        next_done = next_state_nograd["done"].bool()
+        next_done = (
+            next_state_nograd.get("done")
+            .bool()
+            .view(*self.batch_size, *self.reward_spec.shape)
+        )
 
         # merge with tensors with grad function
         next_state = next_state_nograd
         next_state["obs"] = next_obs
-        next_state["reward"] = next_reward
+        next_state["reward"] = next_reward.view(
+            *self.batch_size, *self.reward_spec.shape
+        )
         next_state["qp"].update(dict(zip(qp_keys, next_qp_values)))
 
         # build result
diff --git a/torchrl/envs/vec_env.py b/torchrl/envs/vec_env.py
index af44cc533e5..733de7d1c45 100644
--- a/torchrl/envs/vec_env.py
+++ b/torchrl/envs/vec_env.py
@@ -38,6 +38,12 @@ def decorated_fun(self: _BatchedEnv, *args, **kwargs):
     return decorated_fun
 
 
+def _sort_keys(element):
+    if isinstance(element, tuple):
+        return "_-|-_".join(element)
+    return element
+
+
 class _dispatch_caller_parallel:
     def __init__(self, attr, parallel_env):
         self.attr = attr
@@ -420,17 +426,17 @@ def _create_td(self) -> None:
                 )
         else:
             if self._single_task:
-                self.env_input_keys = sorted(self.input_spec.keys())
+                self.env_input_keys = sorted(self.input_spec.keys(), key=_sort_keys)
             else:
                 env_input_keys = set()
                 for meta_data in self.meta_data:
                     env_input_keys = env_input_keys.union(
                         meta_data.specs["input_spec"].keys()
                     )
-                self.env_input_keys = sorted(env_input_keys)
+                self.env_input_keys = sorted(env_input_keys, key=_sort_keys)
             if not len(self.env_input_keys):
                 raise RuntimeError(
-                    f"found 0 action keys in {sorted(self.selected_keys)}"
+                    f"found 0 action keys in {sorted(self.selected_keys,key=_sort_keys)}"
                 )
         if self._single_task:
             shared_tensordict_parent = shared_tensordict_parent.select(