Under the circumstances you describe (where I am assuming that the quality of both A and B as questions are equal, and that B does not have an adequate answer), I would argue that it may be better to close B (the older question) as a duplicate of A (the newer one) rather than the other way around.

This still achieves the aim of grouping together similar questions, but I think that doing it this way around has several advantages:

1. It is more likely to lead to the OP actually getting an answer. Since old questions that have some kind of answer are unlikely to be revisited, closing the newer question as a duplicate could just end up silencing the question.
   
   There have been numerous occasions where I have seen a question closed as a duplicate in this way, only for the OP of the newer question to then have to push for people to answer the original question.
2. Closing the newer question as a duplicate sends the wrong message to the OP. Having a question closed indicates that on some level, there was something inappropriate with the question. However, in this case, I think the OP acted correctly: in seeing that there were no available (complete) answers to a question, they asked the question.
   
   
3. Once the question is closed, the OP will justifiably be in a quandary: their question has been closed, and yet they still have nowhere to go for an answer. It takes an assertive user to push this point. A less assertive user may just go home empty handed.

Under the circumstances you describe (where I am assuming that the quality of both A and B as questions are equal, and that B does not have an adequate answer), I would argue that it may be better to close the older question as a duplicate of the newer one rather than the other way around.

This still achieves the aim of grouping together similar questions, but I think that doing it this way around has several advantages:

1. It is more likely to lead to the OP actually getting an answer. Since old questions that have some kind of answer are unlikely to be revisited, closing the newer question as a duplicate could just end up silencing the question.
   
   There have been numerous occasions where I have seen a question closed as a duplicate in this way, only for the OP of the newer question to then have to push for people to answer the original question.
2. Closing the newer question as a duplicate sends the wrong message to the OP. Having a question closed indicates that on some level, there was something inappropriate with the question. However, in this case, I think the OP acted correctly: in seeing that there were no available (complete) answers to a question, they asked the question.
   
   
3. Once the question is closed, the OP will justifiably be in a quandary: their question has been closed, and yet they still have nowhere to go for an answer. It takes an assertive user to push this point. A less assertive user may just go home empty handed.

Under the circumstances you describe (where I am assuming that the quality of both A and B as questions are equal, and that B does not have an adequate answer)  , I would argue that it may be better to close B (the older question) as a duplicate of A (the newer one) rather than the other way around.

This still achieves the aim of grouping together similar questions, but I think that doing it this way around has several advantages:

1. It is more likely to lead to the OP actually getting an answer. Since old questions that have some kind of answer are unlikely to be revisited, closing the newer question as a duplicate could just end up silencing the question.
   
   There have been numerous occasions where I have seen a question closed as a duplicate in this way, only for the OP of the newer question to then have to push for people to answer the original question.
2. Closing the newer question as a duplicate sends the wrong message to the OP. Having a question closed indicates that on some level, there was something inappropriate with the question. However, in this case, I think the OP acted correctly: in seeing that there were no available (complete) answers to a question, they asked the question.
   
   
3. Once the question is closed, the OP will justifiably be in a quandary: their question has been closed, and yet they still have nowhere to go for an answer. It takes an assertive user to push this point. A less assertive user may just go home empty handed.

Under the circumstances you describe (where I am assuming that the quality of both A and B as questions are equal, and that B does not have an adequate answer), I would argue that it may be better to close B (the older question) as a duplicate of A (the newer one) rather than the other way around.

This still achieves the aim of grouping together similar questions, but I think that doing it this way around has several advantages:

1. It is more likely to lead to the OP actually getting an answer. Since old questions that have some kind of answer are unlikely to be revisited, closing the newer question as a duplicate could just end up silencing the question.
   
   There have been numerous occasions where I have seen a question closed as a duplicate in this way, only for the OP of the newer question to then have to push for people to answer the original question.
2. Closing the newer question as a duplicate sends the wrong message to the OP. Having a question closed indicates that on some level, there was something inappropriate with the question. However, in this case, I think the OP acted correctly: in seeing that there were no available (complete) answers to a question, they asked the question.
   
   
3. Once the question is closed, the OP will justifiably be in a quandary: their question has been closed, and yet they still have nowhere to go for an answer. It takes an assertive user to push this point. A less assertive user may just go home empty handed.