If you cannot walk on an item and want to put an item on top of the item there's a couple of ways to do this. Please note in order for some items to be raised they need to have something under it. Going off of your picture there wasn't a way I could replicate having 2 bookcases on top of each other without placing an item in between them to raise one. For my demonstration, I'm going to use a Brown Pit Demon, but I recommend you check out this TibiaQA question for inspiration: What are some of the unique items that lift/raise items? Please note you don't have to use bookcases and some items will look perfect just as one with an item on top of it :)
1) If you own a house with 2 levels then this trick will work for you. Unwrap 1 bookcase throw one down/up the stairs or ladder. Throw an item that will raise the 2nd bookcase, then unwrap the other bookcase and throw it down/up the stairs or ladder. Please note maybe this won't look right in some places.
2) Now every house has a door so this trick will hopefully work for you. Unwrap one bookcase behind the door, now this part is important...quickly place the item you want to lift the 2nd bookcase inside of the doorway but at the same time, you do that close the door so the item goes over to the other side. Unwrap the 2nd bookcase and repeat.

3) This third way won't work for 2 items that you can't move, but it does work for placing an item on top of an item you can't normally place items on. Stand in the square where you want the item. Unwrap the item you want to keep (bookcase) while staying in the same square unwrap another destructible item that's a container I decided to use a venorean wardrobe. Now open the venorean wardrobe and put the item you want on top of the bookcase inside of it. Use a melee weapon on the venorean wardrobe so it breaks browse the field to remove the rubbish.
Also seen in these related TIBIAQA questions:
How to put an item on top of a furniture from the Store?
How can I put dead human on top of furniture from the Store?