Worth to visit: faq : How should duplicate questions be handled?
Q. Of these questions, I answered question 1 because that was asked earlier. The second question also asks similar question about there are additional questions too. I answered those questions in my answer. Now can the second question be marked as duplicate?
If answer(s) to
question A actually answers to
question B also, then B can be closed as duplicate of A [note].
Questions may be duplicates if they have the same (potential) answers. This includes not only word-for-word duplicates, but also the same idea expressed in different words.
As I discussed at Finding similar questions/posts and new questions whose answers are already present?: which question should be closed as duplicate:
Usually a recent question will be closed as a duplicate of an older question. But this isn't an absolute rule. The general rule is to keep the question with the best collection of answers, and close the other one as a duplicate.
Should I vote to close a duplicate question, even though it's much newer, and has more up to date answers? ensures it:
If the new question is a better question or has better answers, then vote to close the old one as a duplicate of the new one.
You can flag and ask a moderator to merge after closure if they're exactly the same.
Q. When I have an answer of two similar questions both unanswered. Which should I answer the earlier or later?:
In general case, you should answer to old question and consider voting newer question to close as duplicate but it is not a rule that you should provide answer only to older question. In few cases, if the newer question is a better question with more views and votes then you may write/provide answer to newer question and vote older question as duplicate of newer.
Related post: Answer on New Question or Old Question?
The overarching goal is to have one good source of correct information for the question.
Q. Should the inactivity of the OP also be considered? Because many users who have asked high voted questions have gone into hibernation. Due to this people who are new to the site are not gaining any reputation. This implies delay in gaining privileges and resulting in spam answers.
No, I don't think you should consider the activity of OP, instead you should focus on the quality of question.
[Note] : This is mostly applicable with few exceptions like : "Close as duplicate" - what if only the answer is a duplicate?
Btw, This is not an attempt to answer the question particularly according to this or this, rather this is an attempt to provide general answer.