And gain what???
Possibly a lot of money they aren't entitled to.
Not you, but some future owner down the road, years or decades from now.
Because the practice was to use the last two digits of the serial number on some parts, this allows for what is called "force match". This is where someone takes a part from a gun with the last two numbers matching another gun and uses parts from one, on the other.
This creates the impression that the now "all matching" gun has original parts.
Collectors pay more for all matching guns based on the idea that they are all original, and the difference can be large. An all matching Luger might bring twice what the same gun with mismatched parts is worth.
Its fine if you want to "force match" the parts for YOUR gun, you know what you did. But some future owner might not know what you did, and believes the gun is all original, and values it as such.