The short answer
A. Lange & Sohne has never built a watch called the Lange 2. The Glashutte catalog runs Lange 1, Grand Lange 1, Little Lange 1, Lange 1 Time Zone and Lange 1 Daymatic, then moves on to Saxonia, 1815, Richard Lange, Datograph and Zeitwerk. So "Lange 2" is a seller's label, not a factory model. Reference 401.021 does not appear in Lange's published reference tables either. Yellow-gold Lange 1 pieces sit in the 101.xxx block, where 101.021 is a yellow-gold Lange 1 with a solid silver dial, while the 4xx numbers belong to the Datograph family. When a listing calls itself a replica Lange 2 401.021, the number is mostly decoration.
Where the name comes from
Factories and middlemen coin their own names, because a familiar-sounding model is easier to sell than an internal code. "Lange 2" likely started as a typo or a translation slip that then got copied from listing to listing. Some agents also use it to separate an older Lange 1 style case from a later, slightly larger version they market as a "second generation." None of that comes from Glashutte, and none of it tells you which movement is inside the case.
What the watch in those listings usually is
Nine times out of ten the photos show a Lange 1 style layout: an off-center time dial, a small seconds subdial at the bottom right, a two-window outsize date near the top right, and a power reserve arc marked Auf and Ab. The genuine article is a 38.5mm manual-wind watch with the L901.0 calibre, twin mainspring barrels and roughly 72 hours of running time. Copies keep the silhouette and lose the mechanics.
- Date windows: the real outsize date is a pair of jumping discs. Cheap copies print the digits on one disc, so the font is wrong and the two numbers rarely line up.
- Power reserve hand: on a genuine Lange 1 it tracks the mainspring. On many replicas it is fixed, or it only moves when you wind the crown.
- Movement finish: look for hand-engraved balance cocks, screwed gold chatons and Glashutte ribbing. Stamped plates with laser-etched swirls are the giveaway.
- Case size: check the actual diameter and lug shape. A 42mm case is not a Lange 1, whatever the dial says.
- Dial text: letter spacing, the placement of "Made in Germany," and the thickness of the printed minute track all drift on copies.
What I look at first
- Ask for a macro shot of the date aperture with the watch set to a date ending in 1. Misalignment shows up fast.
- Ask for a video of the movement running with the caseback open, not a still photo.
- Check the crown and pushers. If the case is a Lange 1 clone, there should be one crown and nothing else.
- Compare lug-to-lug against the real number before you commit. Wrist fit is the part you cannot fix later.
About the word "Swiss" in the listing
In the replica trade, "Swiss" often means a Chinese case with an Asian 2824 or a Seagull ST25 inside, or a movement assembled from mixed parts. A hand-wound clone of the L901.0 layout is rare and expensive to make, so most of what you see is an automatic with a fake power reserve. If the price is a few hundred dollars, no part of the movement came out of Switzerland. Ask which calibre is inside and what it is based on. Sellers who know their stock answer that question directly.
Legal and practical reality
A. Lange & Sohne is a registered trademark, and counterfeit watches carrying that name are seized at the US border on a regular basis. Importing or selling them is illegal in the United States, which is worth knowing before you list anything or bring a box through customs. On top of the legal side, a replica is not an investment. It will not hold value, service parts are hard to source, and most watchmakers will not touch it. Buy it as a curiosity if that is what you want, not as a stand-in for a five-figure watch.
Bottom line
There is no Lange 2, and 401.021 is not a Lange reference. Treat "replica Lange 2 401.021" as a keyword, then judge the actual watch on its case size, date mechanism, movement and finish. Those four things tell you far more than the model name on the listing.