New answers tagged effects
There are quite a few different ways to do this. The simplest way is to double the existing vocal track, and then shift the copy slight in pitch (by a few cents) and/or time (10-20 ms). You could also shift one towards the left channel and the other towards the right to gain more seeming independence of the voices. Applying a compression effect can also ...
There is Ditto x4 looper http://www.tcelectronic.com/ditto-x4-looper/ I think it does everything you asked for
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