A "duino" became something of a thing, when Arduino open sourced their Arduino hardware.

Arduino and its respective logos are Trademarks of Arduino AG. These parts are not open sourced. This is why you will often see third-party Arduino derivatives noted as "Arduino Compatible" hardware. Effectively this means the only "real" Arduino is one that carries an Arduino name and logo.

Open source hardware means that other manufacturers are free to replicate and distribute their own iterations of Arduino-based hardware designs. Often this means replicating the original Arduino product with minor variations, or changes to hardware. However for all intents and purposes they're usually a direct working clone. After all, the major brain at the heart of any of these microcontrollers is often a brand name chip. They're still great boards and are usually fully compatible with the Arduino IDE too.

Many manufacturers however, use the Arduino open source principles and create their own variants, which may be more specific to a particular function, or simply combine functionality (such as Ethernet) for convenience.

On occasion, some manufacturers won't put their own "FUNduino" or "Duinotech" branding on it (or as in the article, Panduino), and instead try and pass it off as the real thing. Sadly fakes do turn up, often on peer-to-peer purchasing sites. A third party branded board is perfectly legal and part of open source, but a counterfeit board is not.

You can check out the tips and tricks for spotting a fake on the Arduino website.

You can also check out a list of distributors at: https://www.arduino.cc/en/Main/Buy

Your particular retailer may not be listed for a variety of reasons, as they may purchase from a registered distributor too. However, if your product doesn't arrive with a lovely crisp authentic Arduino feel and claims to be one, it may not be.