According to a page, this word is pronounced "ningen"
but according to another page, the readings for 間 are
Are they the same kanji? Is "gen" an unofficial reading or something?
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Sign up to join this communityIt's called Rendaku. Regularly in compound words, though not always, the second part of a compound ends up voiced. So the reading of the kanji is in essence ケン, but with a dakuten (゛) or voice mark added to it. This gives us the reading ゲン as in the word 人間. It's not a very common reading though, personally I can only think of one other word using the ケン reading, and that is the word 世{せ}間{けん}.
Take the two words fire = 火{ひ} and flower = 花{はな}. Together they can form two new words, fireworks = 花{はな}火{び} and spark = 火{ひ}花{ばな}. The reading is the same in both except that when it appears last in a compound it gets voiced.
Why does the last part get voiced sometimes? I don't know, and I don't think anyone definitely knows. It could make it easier to say, or it makes the two parts more connected into a new words rather than the sum of its parts. Either way it's something the Japanese do and worth knowing about.
Edit: Example, both 忠{ちゅう}告{こく} and 中{ちゅう}国{ごく} have the same on-reading for both kanji, however only the latter one gets voiced.
Are they the same kanji?
Yes
Is "gen" an unofficial reading or something?
I'm not sure if it's unofficial, but you can and sometimes do read it as ゲン。
You occasionally voice some kanji readings, but I can't exactly explain why. It has to do with the sound before the character, but I haven't studied enough kanji to make sense of it.
Another great example of this is: 手紙{てがみ} 。 Looking at jisho.org, you will find that がみ is not listed as a reading, but it is still read てがみ。
I'm not privy on the rules if there are any, but this sort of thing happens a lot.