If you select the image file (that was sliced into multiple sprites) and drag that into the editor it will keep the layout of the sprites. When selecting multiple individual sprites and dragging those in, the tool treats them as just sprites, and does not recognize that those sprites are part of the same texture, so it just lays them out from left to right.
If the problem is still present after trying this please report back to me, because in that case it is a bug.
I may not have expressed myself clearly. The sprite sheet image I dragged in have been edited by me. Some of the tiles are 16*16, and some sprites are larger, such as houses and trees. However, when I put them into the better rule tile editor, they did not maintain their original state.The larger sprites has been scaled into 16*16.