As the Bunny, you want to take bounces once in a while because a platform may be very close to you. Small jumps are needed because sometimes there is a medium-sized gap sometimes between platforms and you will finish the level easily. The boxes are not needed if you are playing the Bunny.
As the Duplicator you can use the boxes but you can also beat the level with the path of normal tiles. Make sure your duplicates are near you so they do not change gravity, you can jump on them, or replace you when you fall into the void. If you are going the normal tile route you want to keep your duplicates alive because when there is a big gap between platforms you need to jump on your duplicates.
If a platform is very close to the platform you are on you can just normally jump with the Duplicator because of his small jump height. If you are going to use the boxes to your boxes be careful because duplicates can change the gravity of the tunnel if they touch a box on a side of the wall, so be on the lookout! Be careful when jumping onto a box at the beginning of the level because if you miss the jump you will fall into the void. If needed jump on your duplicate to reach a box. If you have no other way to another box jump into the normal tile route if near you. And at the end of the level, you are about to fall. Make sure you have a duplicate reaching the end of the level so you can become that duplicate. How? Well, duplicates jump higher than you do.