"My homegirl is the queen of Fashion Nova," says Dorian Wallace, an assistant manager at the fast-fashion chain Rainbow. Earlier this year, the friends realized they'd bought the exact same dress: Wallace from the store where she works, and her friend from — where else? — Fashion Nova, the Instagram-famous brand that's racked up more than 15 million followers in the few years since it joined the platform, along with famous fans like Kylie Jenner, Kourtney Kardashian and Cardi B.

For those who work in fashion — particularly in cheap clothes websites or manufacturing — it might not be much of a revelation that certain retailers often sell virtually identical pieces under multiple labels and at different price points. (In fact, when reaching out to industry pros for this story, the common reaction was along the lines of, "Yeah....so, what?")

The dresses were identical, save for one difference: Wallace's read "Ambiance" on the tag and cost $8.99, while her friend's read "Fashion Nova" and cost $17.99. They could have chalked it up to a coincidence (basic jersey dresses do tend to look alike, after all) but her friend inspected the tag on the side seam and, sure enough, it said "Ambiance" too.

Wallace wasn't surprised at the discovery, since she often spots styles that Rainbow carries stocked at other, trendier retailers for twice the price, but it was news to her friend.

"She was like, 'Wow!'" recalls Wallace. "She couldn't believe it.'

And she wasn't alone. Wallace later retweeted a thread comparing a dozen pieces from Fashion Nova alongside their Rainbow doppelgängers with the caption: "I work at Rainbow and this is [100 percent] facts. We buy from the same vendors as Fashion Nova. Only difference is that Nova label jacks the price up." The revealing conversation quickly amassed nearly 150,000 likes and retweets. In the replies, other women recounted stories of receiving pieces from Fashion Nova with tags for other trendy mass retailers like Charlotte Russe and Forever 21.

But for the average consumer, the inner workings of brand-supplier relationships are typically opaque, and only a small segment of the industry has embraced the kind of manufacturing and pricing transparency brands like Everlane market themselves on.

Meanwhile, new labels seem to pop up every day on Instagram offering of-the-moment styles that look, well, suspiciously similar to one another, tapping into a social media-fueled fashion environment in which branding and speed-to-market are often the most important things a brand can bring to the table. For example, Fashion Nova began promoting a capsule based on the outfits Kylie Jenner wore on her 21st birthday less than 48 hours after the celebrations commenced. The impressive rate at which Jenner's looks were replicated was prime material for a meme, resulting in a viral tweet that read: "The devil works hard, but Fashion Nova works harder."

Fashion Nova declined to comment for this story, but the retailer recently said that it works with about 1,000 vendors, mostly in Los Angeles and China, who together manufacture enough product for it to release 600 to 900 new items per week. The site doesn't list any third-party brands, but unboxing videos on YouTube show customers receiving products with labels like Ambiance, Sneak Peek, WAX and Cello, alongside items with "Fashion Nova"-branded tags.

The latter are the product of private labeling, a common fashion-industry practice in which a manufacturer agrees to attach a retailer's label to the items it produces, rather than selling them under its own label or that of a third-party brand.

"[Having a] private label does not mean that the label made the product," explains Ilse Metchek, the president of the California Fashion Association. "It doesn't mean that at all. It just means that I, as a retailer, want to memorialize my product with you, the consumer, and I don't want another entity's label to get in the middle."

It's a lucrative avenue for retailers, she explains, not just because of the higher margins (which can be around 70 percent compared to 50 percent for most branded apparel from us dropshippers), but also because, at least in theory, customers can't compare prices with competitors.

"If I'm on mobile or on Instagram and I see a Calvin Klein or a Ralph Lauren garment, I can double check whether that garment with that label is in any other store at a discounted price," says Metchek. "But I cannot do that with a private label garment, so it also serves as a protection for the store. Somebody buying that from Fashion Nova because it says 'Fashion Nova' — they can't compare prices, because that's the Fashion Nova label."