[2.0.28] Ghost Tiles Can Be Placed on Existing Tiles and Remain Indefinitely

[miege1000]

I've noticed this on Gleba, but other types of tiles might be affected too.
https://imgur.com/a/IhQIRSQ

Steps to reproduce:
1. pick some tiles where you have placed Artificial jellynut soil.
2. put ghost tiles of regular landfill on top of them
3. before the landfill has been put down, you can now put ghost tiles of artificial jellynut soil, replacing the landfill ghosts
on top of already built artificial jellynut soil.
4. robots will come and try to place the jellynut soil down, but they are unable to, showcasing the sparks animation and they will stay occupied forever.