Insert multiple slides

To build up a slideshow I always have to insert slides one by one. Is there no way to insert slides by the number, for instance 15 at once?
Also: I often have to prepare a presentation which contains a set of slides with minor variations within the slides itself. Now I can copy for instance 2 slides 8 times by choosing the menu “insert - duplicate slide” 8 times in a row, and then apply the variations to each slide. But I can’t copy the slides 8 times in one move. Or can I?

Copy more than 1 slide:
Change to Slide Sorter view of source presentation > select all slides you want to copy > ctrl+c > go the target presentation > change to Slide Sorter view > ctrl+v

8 times in one move is not possible you need to use the dublicate function or copy & paste function 8 times.

I recommend to have a look at the free guides which you can download from http://www.libreoffice.org/get-help/documentation/