This is mainly in reference to this question being closed as a duplicate to this question. I understand that questions should not be asked again, because they don't like the answers, bounties are the way to attract different answers on a question (related meta), however this is not the case for this question. The two questions, though similar/related, are fundamentally different, yet the newer one was closed as a duplicate of the older because some of the solutions from the older one could work.
I personally feel this is bad practice, and that questions that are different should be left alone, even if a related question has answers that might work.
The reason that they are different, is because they ask for ways to clean different parts of the keyboard. One asks cleaning the top of keys, the other cleaning under and between. While some overlap may occur, there is also a certain amount of exclusion as well. These (1, 2, 3, 4) answers all would not solve the problem of cleaning under the keys.
Duplication should be used for exact duplication. If the person had instead posted a comment asking his question, he would be told to post a question if he had one instead of doing it in a comment. If he placed a bounty on the question looking for answers to clean underneath his keys, it would be deviating from the original question. It would be like placing a bounty on a question about cleaning car windows to ask how to clean car tires. Though related, and some of the answers may overlap, they are different questions.
Yes, while overlap in answers is indication that the questions may overlap too, it does not mean that they are duplicates.