Upvote:4
Correcting conflicting claims
It's normal, and something can be done about it. In each individual article, add material with verifiable, authoritative sources from the literature about that article's topic, and/or correct existing material based on the sources. If a change you make is reverted or challenged, discuss it on the talk page.
The key thing to note is that contradictions between Wikipedia articles are not evidence that either article should change. The reason for this is that Wikipedia is not a reliable sourceβaccording to Wikipedia's own standards. If you are working on article B, and article A contradicts something in article B, it doesn't matter, because Wikipedia's article on A is not a reliable source for B.
If the sources for topics A and B contradict each other, then their Wikipedia articles should contradict each other, too, because Wikipedia's job is to reflect the existing literature, not correct it.
Mutatis mutandis for articles about topic A in different languages.
Judging conflicting claims
If you are only trying to determine which of the two competing claims is true, then you must check the sources cited (and possibly other literature, of course) and judge for yourself. Wikipedia policy requires that all factual claims have sources indicated in the article. These are shown by numbers in brackets, which link to full academic citations at the bottom of the article. Wikipedia is not always reliable about information about a topic, but it's a great entry point into the literature about nearly any topic.