Some videos have multiple different titles, which I guess reduces duplication :) (not that I think duplicating a string a few times in html matters at all. meta tags exist for a reason)

For example, if you go to https://www.youtube.com/watch?v=PvzBWFGEz8M, you'll notice the title in the browser tab differs from the title below the video.

Relevant html snippets are:

    <title>トーキョーゲットー - Eve MV - YouTube</title>

    <meta name="twitter:title" content="Tokyo Ghetto - Eve MV">

The actual title shown below the video is the english one, not japanese, and I think is sourced from javascript data.

I find it fascinating that youtube translates the title in some places users see it, but not all places, and only on a small subset of videos. It's pretty weird.