expression, noun
Used when two or more events happen at the same time or in a similar way by chance, without any causal connection.
同じ誕生日だなんて、偶然の一致ですね。
It's a coincidence that we have the same birthday.
彼の話と証拠が偶然の一致を見せた。
His story and the evidence showed a coincidence.
Compound of 偶然 (accidental) + の (possessive particle) + 一致 (agreement). The phrase is a straightforward combination of its parts.