Wǒ zài zhè jiā gōngsī gōngzuò chàbuduō shí nián le. 我在这家公司工作差不多十年了。 Wǒ zài zhè jiā gōngsī gōngzuò le chàbuduō shí nián . 我在这家公司工作了差不多十年。 Wǒ zài zhè jiā gōngsī gōngzuò le chàbuduō shí nián le. 我在这家公司工作了差不多十年了。 these are all CORRECT! I have been working in this company for about ten years. if you really want to know the differences between these sentences.i 'd tell you that no differences.every Chinese could barely lost you while you say any of these sentences.

It looks correct to me. I would translate it as: I have been working at this company for about 10 years. The double 了 (le) is used for ongoing durations. Basically present perfect with duration of time. You can read more about it here: https://resources.allsetlearning.com/chinese/grammar/Expressing_ongoing_duration_with_double_%22le%22

对的。第一个le是助词，第二个le是语气词。

Wǒ zài zhè jiā gōngsī gōngzuò le chàbuduō shí nián le。This sentence does not have any problem from the grammar. Or you can remove a "Le" is no problem, a more "Le", to strengthen the tone, more fully express the mood of the speaker

This sentence is wrong, this involves the results complement problem. cha bu duo shi nian" is the "results" complement “gong zuo” So here we can only say "gong zuo cha bu duo shi nian le" as we say "cha gan jing le" rather than "cha le.gan jing. So it should be said that this sentence：wo zai zhe jia gong si gong zuo cha bu duo shi nian le .or:“wo zai zhe jia gong si gong zuo le cha bu duo.shi nian”