Wrong gender in 20 and 24 weeks ultrasound

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Is anyone ever experienced this?
My friend had two ultrasounds one in her 20 weeks and another one was her 24 weeks tech told her it's def a girl but boy born at her 39 week. She had big baby shower since it's her first child and we all brought her pink stuff. 😂😂
Is anyone else here has same experience? I am just curious to know how it's possible