No, "duplicacy" is not a standard English word. The correct term is "duplication" or "duplicity."
Both are grammatically correct, but the normal word-order is "you are correct." The inverted word-order of "correct you are" is used for an emphatic, ironic or humorous effect.
No it isn't a grammatically correct word.
no
Yes, "evidenced" is a grammatically correct word. It is the past tense of the verb "evidence," meaning to show or prove something.
The word "they're is pronounced grammatically correct. It is the shortened version of the words "they are".
The correct spelling of the word "grammatically" is G-R-A-M-M-A-T-I-C-A-L-L-Y.
yes it is a real word. It is also correct grammatically and more stupid is not correct.
Yes, it is grammatically correct to end a sentence with the word "so." However, it may be informal or conversational in style.
Yes, it is.
The word "they're is pronounced grammatically correct. It is the shortened version of the words "they are".
No, it is not. The "question word," why, should be at the beginning of the sentence. Why was she promoted?