In your case, I'd say never clone a track. There are reasons you may wish to do it, but for now, forget them (for now at least), they'll almost definitely do you more harm than good.
It's all about composition and performance here, I believe.
If you're performing a harmony in which the backing vocals are mimicking the main vocal, I would start by recording multiple takes and begin by panning these around to create a nice wide vocal sound. You may also benefit by using a different mic. Eg use a condenser for the main vox but switch to a dynamic to do the backing vocals. You could also try eqing the high end out of your BV (backing vocals).
You can vary the way you sing to create distinction and interest. Singing some of the harmonies with a 'soft' nature and some with a more aggressive style can result in an interesting blend with a nice warmth but edginess to it. Play around with it.
You may notice with lots of voices going on, sharp sounds tend to all be slightly out of time (like 'p' and 's' sounds). This makes it VERY obvious to the listener that there are multiple vocals. If you want this, that's ok, but sometimes you don't. In this case, you can physically practise singing the lyrics without those sharp sounds. Almost like singing with a lisp! It will sound weird, but blended with the main vox can sound great and give it a huge, full sound, but without sounding multitracked. Another option is to manually edit each on out. This is NOT fun! You choose.
If you really want to create interest, you may wish to sing the harmonies with different notes. You can sing them exactly the same, but one octave below, or above. You can sing it the same but maybe a 3rd above. I think a 3rd above tends to generally sound well but I believe singing a 5th above can sometimes result in clashes. Not to sure on this here as my music theory is a bit rusty... Experiment! Try playing your main melody on keys and then plan your harmony over the top of that piece.
Bottom line, your processing you apply in X1 should simply be there to enhance an already great sounding harmony. If it doesn't sound great after a quick 2 seconds of adjusting volumes and maybe panning (if you're going for a big sound), then you're going to really struggle to get a great end result. Compose your harmonies well, record them well, and everything will fall into place. X1 is not a magic potion, YOU are the magic! So make it happen! (was that cheesy?... haha)