Hi Kristyna,
Agreed very annoying. If you have exported bookmarks from ie you can do what I did - which saves some typing at least. Open the file in Opera (it is HTML). The links for all your bookmarks are there in a list. Just highlight eachone and open in a new tab. Then go through each one in turn and add to your stash. Not a perfect solution but saves some time.
Cheers Maddox