Short answer

A. Lange & Söhne never made a Lange 2. Search that phrase and what you actually mean is the Lange 1 Perpetual Calendar, and the replica market for it splits into three clear tiers: quartz pieces that only move a date window, automatic watches with a decorative calendar, and a small number of modified automatic movements that genuinely track month lengths and sometimes a leap year. Knowing which tier a seller is offering is the whole game, because the price gap between them is large and the photographs all look the same.

What "perpetual" means on the genuine watch

A perpetual calendar knows that February has 28 days, that leap years add a 29th, and that century years skip the leap day unless divisible by 400. The Lange 1 Perpetual Calendar carries that logic alongside a moonphase and a day/night display, and it is built to stay correct until 2100. A real perpetual module is a complication inside a complication: cams, levers and a program wheel stacked on top of the base movement. That is why the genuine article costs what a small house costs.

What replica versions actually do

This is where listing copy gets loose. I sort them like this:

• Quartz calendar watches. Battery movement, with the date and often the moonphase driven by a separate stepper. The moonphase is a printed disc on a 29.5-day cycle with no link to the calendar. Cheap, thin, dependable, and obvious as quartz the moment you feel the second hand tick.
• Automatic with a decorative calendar. Day, date, month and moonphase all present and all moving, but the month does not know about February. You correct it with a recessed pusher several times a year. Convincing on the wrist, less convincing on a watchmaker's bench.
• Automatic with a real calendar module. The base movement is modified, or a module is bolted on, and the calendar handles short months correctly. Some of these include a leap-year indicator. These exist, and they are the only versions worth serious money. They are also thicker, heavier and far rarer in the channel than the listings suggest.

What I check before buying

Photos hide a lot, so I work through the same list every time:

• Subdial placement. The month and moonphase rings have to sit where the dial was designed for them. If the month ring drifts off-center or the printing crowds the date aperture, the case was built for a different layout.
• Date aperture. The Lange outsize date is two separate discs with a clean gap between them. A single printed disc shows instantly at an angle.
• Moonphase disc. Look for a printed sky with stars and a defined moon, not a flat blue circle with a dot glued on.
• Leap-year display, if the seller claims one. Ask for a photo of it in a different position, or a short clip of the date rolling over at month end.
• Case thickness. A calendar module adds height. If the quoted dimensions match a plain time-and-date model, the calendar is decoration.
• Correctors. Real perpetuals use recessed pushers on the case band. If correction happens through the crown alone, you are in tier two.
• Finishing. Hand-engraved balance cock, blued screws, gold chatons around the jewels, and clean ribbing or perlage on the plates.

Living with one

Never set the calendar between roughly 9 p.m. and 3 a.m., when the date mechanism is engaged and a pusher can shear a tooth. Use the corrector tool that ships with the watch, not a paper clip. Wear it or wind it on a routine, because a stopped calendar needs re-setting, and on tier-two watches that means cycling through months by hand. If a local watchmaker declines to open the case, that tells you something about the movement inside.

Honest expectations

A replica Lange perpetual will not fool a Lange owner across a table, and it will not run for the same decades. What a good one can do is give you the dial, the layout and the feel of a five-figure complication for a fraction of the money, with a working moonphase and a calendar that mostly behaves. Buy the movement, not the photograph.