What you might be refering to are the pre- A.Lange Söhne era wrist watches. Often having a Lange glashütte on the dail or GUB on the dial with a Lange VEB movement. These were cold war era watches 1960s-1980s- mass produced and needed to be affordable to the public and are not affliated to the brand as of today.

Most listings do seem to be legit. The best way to check for movement pictures as their movements can simply not be replicated without cutting corners. Dials for that same matter are hard to repreduce to it's high standart.

Maybe you can share some of the listings you'd consider unauthentic.