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I don't know if anyone noticed, but in many modern day songs, the vocal seems as if it is being played twice with a small delay to prevent it from being noticed. Alternatively, it is accompanied by a musical note that is identical to the singing voice.
Does this technique have a name? Is it used to enhance the vocals artificially? Some examples:1:35 2:35 1:39 (seems like it's even played three times!)
Focus purely on the vocals from a few seconds before to a few seconds after the time provided, it sounds as if the vocals are playing twice.
Here's another example where the chorus doesn't inhibit this behaviour, but the bridge does1:17 until mid-chorus