These are not mistranslations

But that's what people call them.
They are most likely just poorly produced English sentences by people who do not speak English as a first language and who are therefore unaware of their inadvertent double entendre.
But unless there was an original text, and the person producing this English was intending to reproduce that source text accurately and faithfully, and had failed in the actual process of transferring that meaning and pragmatic effect, and unless the reasons for their failure are explained, then who knows if they are "mistranslations"?
More likely this is just English speakers laughing at foreign people, with the flipside being the expectation that all you need to be a translator is to be able to speak English well.

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