Of course people will post duplicate ideas. Since very few will bother read a bunch of previous posts, also waste of time. If You really want to reduce repetitions then you have to have (a link to) a list of suggestions in this first post, frequently updated and preferable with status.
Same with bug reports, but also have an "fixed" section in case of a recurrent one.
Also have an easy option to upload files; pictures and saves and logs. For such I do not like using e-mail or Imgur or similar.