I have recently purchased Elements & Premiere Elements 15.
Whilst trying to create an instant movie using my own music of 7 mins 24 secs I noticed that the length of film created is 14 mins 48 secs (i.e. double) and it used the same music twice.
Any idea how I can resolve this?
I don't know why what happened happened. It's possible related to the InstantMovie template you used and it's possibly related to the media or music format you used to compose the InstantMovie.
However, you can right-click on the InstantMovie on your timeline and select the option to break it apart. This will turn your InstantMovie into a sequence of clips and effects which you can edit and remove as needed.