An Instagram account that juxtaposes side-by-side images of strikingly similar work by different artists has become a popular platform for debating issues of appropriation and plagiarism in the art world—and for shaming copycats.

The account @whos____who, whose owner is anonymous, has gained nearly 13,000 followers since it quietly launched in January 2016. The first post compared a blue-faced portrait of a man by the Wisconsin-based artist Tyson Reeder with another one by New York painter Nicole Eisenman.

The handle never editorializes; it merely lists the artists’ names and lets users decide whose work is whose and, more often, who copied whom. But the comments section has become a heated battleground to debate what constitutes stealing, who has the power to take visual motifs, and who ends up getting taken from.

One recent dispute centers on a current show of contemporary artist Josh Smith’s paintings of watermelons at Eva Presenhuber in New York, on view until June 17. @whos____who pairs one of Smith’s watermelons with a similar painting by Mose Tolliver, the late African-American folk artist who died in 2006.

“A good example of how Blackface works casually in art now,” commented the user @genuinedanger. “Black visual artist makes work years earlier that represents specific tropes or imagery used against Black ppl then nonBlack makes a watered down of it later for profit which renders Blackness as materiality, a renewable resource n property.” (Smith, who is white, was born in 1976; Tolliver was born in 1925.)

Another user, @helloradlo, responded with sarcasm: “ya I’m sure josh smith stole that watermelon.” Later, someone else complicated the question by throwing out the name of another historical painter of watermelons, the Mexican modernist Rufino Tamayo. (A representative at Eva Presenhuber did not respond to a request for comment.)

But @whos____who isn’t always out to stir controversy, it seems. Sometimes the comparisons merely identify absurd, funny, or played-out tropes in the art world, like the painted mattress phenomenon, a motif taken up by artists including Kaari Upson, Wade Guyton, and Kelley Walker. Another apparent trend? Artists hanging bathrobes on walls.

See more images from the eagle-eyed feed below.