Re-Ditto

When creating a Distaff Counterpart, Captain Ersatz, or similar character, some writers are smart enough to realize that fans are going to inevitably compare them to the original character, and will almost inevitably cry "rip-off", especially if they were created by editorial mandate. So one way to make them viable and differentiate them from the original character is to make him or her generally similar, but different in specific details, and deliberately develop them into another direction.

However, somewhere down the line, an unfortunate situation will often occur where a later writer just treats the new character as a rip-off of the older character, and intentionally retrofits them to be more similar, in powers or even personality.

This is especially dangerous if the character could be considered a Legacy Character, since that route lets a writer kill off an older character without upsetting the general tone of a story.

Examples:
 * The Post-Crisis Superboy was different in several ways from Superman, due to being an attempt at cloning the original that had to be stabilized with human DNA. He had no vision powers, and all the powers he did have were based on the Post-Crisis explanation of Kryptonian abilities as a form of specialized Psychic Powers; he had "tactile telekinesis" which simulated super-strength, flight, and invulerability, as well as a "wild talent" which let him use the tactile TK to blow things up. Later writers just made him essentially a mini-Superman, and Hand Waved it as "his Kryptonian physiology maturing".
 * They also radically altered his teenlike personality, mainly by stuffing his girlfriend in the fridge, and changed his DNA from "mostly Paul Westfield with a few Kryptonian codons" to "half-Superman, half-Lex Luthor". How the world's most advanced genetics research facility which had studied him intensely for years missed that one lies unexplained and obvious.
 * The appeal of Bart Allen, a.k.a. Impulse, was how different he was from the Flash. Mark Waid specifically did not want a new Kid Flash; instead he created a young speedster with a mind like a Mexican jumping bean, nothing like a normal superhero -- hence the name. This changed in Geoff Johns' tenure, when Bart mysteriously sobered up and took on the Kid Flash identity. By the time he was pushed into the role of Flash, the character was unrecognizable, and fans weren't interested in reading about him—prompting DC to backpedal furiously.
 * Marvel had Spider-Man do this to himself during the hated Clone Saga. I think. Or something. This troper gets confused thinking about it.
 * Specifically, the clone decided to become a different superhero—still a ripoff but now obviously not Spider-Man.
 * He actually split the difference with the original. He was introduced in the first place because the original had developed away from wisecracking but still angsty roots into a dark grim vigilante who nearly shed his human identity altogether. So the clone got the original personality and the original got to keep the original costume and name till they finally made their saving throw.
 * This happens a lot with Ultimate Marvel—for instance, Ultimate Pyro isn't supposed to be a follower of Magneto, but he is if the writer is only familiar with the mainstream Pyro.
 * A particularly egregious example is Ultimate Doom. He started off as a metallic satyr who ran a small Free Zone in Copenhagen. Next time we see him, he's back to being the magic using ruler of Latveria. Also, he lost the goat legs, and even later on seems to turn back into flesh. Somehow.
 * Black Adam has a minor case of this. At first he was a major enemy and Evil Counterpart to Captain Marvel. Then Geoff Johns took a liking to the character and DC began to use him as a type of replacement Captain Marvel. It was retconned that he had a case of Bad Powers, Bad People that was what actually made him evil, and he acquired his own "Black Marvel Family" similar to Mary Marvel and Junior. It feels like he's been made into a Darker and Edgier version of Captain Marvel, with his own supporting cast.
 * Jerry Ordway kind of set the scene for this, although he did it the other way round: in his version Teth-Adam is a demon-worshipper who tried to conquer Egypt, and Theo Adam is a thug posessed by him. Both underwent a Heel Face Turn, but Theo's was more dramatic, since he made a Heroic Sacrifice to save his sister's soul. In Johns's version, Captain Marvel explains to the JSA that Teth-Adam is a noble ruler, but Theo Adam is an unrepentant murderer.