同姓どうせい (dousei)

日本にっぽんでは 夫婦ふうふ 同姓どうせいが 一般いっぱん 的てきよ。

In Japan, it's common for a married couple to have the same surname.

韓国では１９９７年に法律が変わり同姓同士でも自由に結婚できるようになった。

In South Korea the laws changed in 1997, and people with the same family name can freely marry each other now.

異音同姓に一色田がある。

There is Isshikida as the same surname but with a different pronunciation.

異音同姓（わたりだ）渡田がある。

As the same surname with the different sound (pronounced as Watarida), there is

私わたしは 私わたしと 同姓どうせい 同名どうめいの 女おんなの 人ひとをしっている。

I know a woman whose first and last names are the same as mine.

大坂の陣では同姓の誼で毛利勝永の部隊にいたとある。

It is recorded that he was in the army of Katsunaga MORI at Osaka no Jin (The Siege of Osaka) for the sake of having the same family name.

渡田.異音同姓（わたのべ）に渡野辺、渡延、渡野邊がある。

As the same surnames with the different sound (pronounced as Watanobe), there are

天皇の御名と同姓なのは畏れ多いと大伴氏が判断したからだといわれている。

This was because the Otomo clan believed it was too presumptuous to have the same name as the Emperor.

渡野辺, 渡延 or 渡野邊.両長召抱人に同姓の沼尻愛次郎がいるが別人。

Aijiro NUMAJIRI (a page) had the same family name but was a different person.

現在では、同姓の分家との関係で用いられないかぎり、ほぼ「家元」の言いかえである。

Now, as long as it is not used when the branch sect shares the same surname, "Head of the School" is almost an equivalent saying to "originator of the sect".

彼らは同姓だが何のつながりもない. They have the same family name but are not in any way related to each other.私は私と同姓同名の女の人をしっている。

I know a woman whose first and last names are the same as mine.