BUG: Duplicate _controllers in Flight.TimeNodes.merge() (#931)

* Fix: Duplicate merge of _controllers in Flight.TimeNodes.merge()

* BUG: Fix duplicate controllers in Flight.TimeNodes.merge()

Update changelog

---------

Co-authored-by: ZuoRen Chen <zuorenchen@outlook.com>

Author: zuorenchen

CHANGELOG.md

@@ -59,7 +59,7 @@ Attention: The newest changes should be on top -->
 - BUG: energy_data plot not working for 3 dof sims [[#906](https://github.com/RocketPy-Team/RocketPy/issues/906)]
 - BUG: Fix CSV column header spacing in FlightDataExporter [#864](https://github.com/RocketPy-Team/RocketPy/issues/864)
 - BUG: Fix parallel Monte Carlo simulation showing incorrect iteration count [#806](https://github.com/RocketPy-Team/RocketPy/pull/806)
-
+- BUG: Duplicate _controllers in Flight.TimeNodes.merge() [#931](https://github.com/RocketPy-Team/RocketPy/pull/931)
 
 ## [v1.11.0] - 2025-11-01
 

rocketpy/simulation/flight.py

@@ -4589,7 +4589,6 @@ def merge(self):
                     tmp_dict[time]._controllers += node._controllers
                     tmp_dict[time].callbacks += node.callbacks
                     tmp_dict[time]._component_sensors += node._component_sensors
-                    tmp_dict[time]._controllers += node._controllers
                 except KeyError:
                     # If the node does not exist, add it to the dictionary
                     tmp_dict[time] = node