[Question] Get two different results

[ExplorerX-Wang]

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• I have read the documentation https://safety-gymnasium.readthedocs.io.
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Questions

I've just started learning this repository, and the following is my trial.

env = safety_gymnasium.make('SafetyPointGoal1-v0',render_mode = "human")

# 重置环境获取初始观察值
obs, info = env.reset()

for i in range(1000):
    action = (0.01,0)
    obs, reward, cost, terminated, truncated, info = env.step(action)
    print("agent velocity", env.task.agent.vel)
    print("Velocimeter :", obs[3:6])    

result is 
agent velocity [-0.28120238  0.10492423  0.        ]
Velocimeter : [0.29999554 0.00930329 0.        ]

Why are they different? and which one is the real velocity?