I just highlighted the slide, copied it, and in the destination file where i
wanted it pasted, i clicked off all of the slides on the left side and just
chose paste
That will work as long as you don't have a need to retain the formatting of the
slide from the other presentation. Insert > Slides from Files gives you that
capability and it's actually easier to use since you don't need to open the
source presentation and you can select multiple slides at once and insert them
in the target presentation.