Don't be embarrassed, OP; you're not the first nor the last to get embarrassed before a user is told that a question is not new to the forum. We can't manage newcomers and regularly send them to read the same threads that have already been created thousands of times. Over time, everyone learns to use the forum, and the questions stop. And the fact that old users are forced to answer the same questions, in a way, becomes ridiculous. Someday, all answers from one user will be considered plagiarism in some sense. 
This will not necessarily be the case. Answers to the same questions may change over time, for example due to advances in technology or new information. Therefore, I believe that answers to the same question at different intervals of time can have at least very useful additions. Even in repetitive topics, it is possible to discuss the issue from a different angle and take into account previously missed nuances. So, I agree that there is no need to be shy about asking your questions.