Yes, that should help. A checksum is a number derived from the contents of a file. It is most often used to verify the integrity of a file. For example, when you download a huge GNU/Linux disk image, its checksum is usually noted next to the download link. Once you have downloaded the disk image, you use the same method the original checksum was calculated with to calculate your own checksum, and if they match, you can be confident that it is the same file.
Since the exact same files have the same checksums, but even the most tiniest change gives you a different checksum, Bunkerchan can use checksums to determine if two files are identical. When you upload a file, it checks if its checksum is already present on the server, and if it is, it can be safely discarded as the exact same data is already there and can be used instead of it. In our case the file is missing, so Bunkerchan will store it, but when the old missing file is requested again, it finds the newly uploaded identical file.
Bunkerchan uses MD5 as a checksum, if you look at URL of the image you just posted, it is the 32 characters after the last slash but before the "-imagejpeg" part: https://bunkerchan.xyz/.media/f4b8d8c0f39d6531ae596f16c667eedb-imagejpeg.jpg
On GNU/Linux you can calculate the MD5 checksum of a file with the "md5sum" command, based on this I can predict that the URL of the image I am posting will be: https://bunkerchan.xyz/.media/4858d747290d44a52ba878d72b2f2f21-imagejpeg.jpg
Boorus usually also let you search by md5, for example: https://safebooru.org/index.php?page=post&s=list&tags=md5%3a4858d747290d44a52ba878d72b2f2f21