Is it a common practice to change the title into something different? Sometimes they change the title into something different, and by different I mean it's not an English translation. An example here is Rurouni Kenshin. Although it state that:


  Rurouni Kenshin is subtitled "Wandering Samurai" in some English releases.


which makes it the closest translation, as a rough translation of the title would be "Kenshin the Wandering Swordsman". But they also use the name Samurai X for this anime title.


  The English-language versions of the OVAs, as well as the film, were originally released as Samurai X in North America, although the original name was included on the later DVD and Blu-ray Disc releases.


But it's not only in North America, as they also mentioned


  Sony Pictures Television International created an English-language version of the series, titled Samurai X, that airs outside of the United States


I don't know if there's another anime that also does this, but I've never seen something like this recently.
This occurs pretty often, it is called Cultural streamlining


  To accommodate American viewers, anime dubbed in the United States is usually modified to suggest it occurs within the United States or a fictional country thus resembling it. This is commonly achieved by substituting Japanese elements in a series by elements drawn from American popular culture, modifying food or other products to resemble their American equivalents and by replacing Japanese writing with English writing.


A very simple example as was given on the wiki is Ash from the Pokemon series carrying a sandwich in the American version while in the Japanese version he carries a onigiri

The same counts for the titles of those kind of series, aka the wandering samurai instead of Rurouni Kenshin. Because most of their audience would not even know what a Rurouni is. 

Changes such as Samurai X usually are done for audience stereotyping, a series called Wandering samurai is less likely to be watched by a female audience. While the name Samurai X is also more attractive to the female audience, which broadens their audience for more income of the series. 

In the end all Renaming of characters/titles is mainly for marketing purposes.