A post that is the same or inferior to an already existing post. This tag only applies to inferior posts that were uploaded after an already existing identical post.
Duplicates should not be confused for the following:
image sample, an image typically used by sites to load images faster.
md5 mismatch, an post that has a different md5 from the file at the source.
revision, a post that has been revised by the artist from a previous version.
variant set, posts with a similar base, but non-trivial differences.
scan, a post that has been scanned from another source.
Resized posts. Note that duplicate resized posts should not be tagged with md5 mismatch.
Images of generally lower quality; often a result of jpeg artifacts.
Before you upload something, check if it has already been uploaded by using the IQDB image search or the "Find similar" button.
Both duplicates and pixel-perfect duplicates must be tagged manually. There is no automated system in place to accurately tag duplicates given how easy it is to confuse them for the above (with exception to image samples where the original is already uploaded). Pixel-perfect duplicates are no longer automatically tagged; refer to its wiki on how to check for them.
Notes:
Do not flag a duplicate post for deletion if your only reason is that the post is a duplicate. Parent them to the superior image instead.
Check for differences with DuplicateBooru if you are unable to confirm with your own eyes.
Filesize alone does not determine the superiority of an image. For example, for a jpeg with the same resolution as another, the one with less artifacts is superior.
Related tags
Not to be confused with multiple sources, although they may overlap sometimes.
multiple sources is about outside sources -- it means that multiple copies are available outside Danbooru.
duplicate is about Danbooru -- it means that we have multiple copies of the same image.
