It won't hurt you or the liquid any more that way, than the way it came. I've tried some flavors that I've improved by doing so. Nothing you do when you mix them will change the common ingredients. An e-liquid is mainly composed of propylene glycol (PG) and vegetable glycerin (VG).
The relationship between these two is different and depends on the type of liquid you choose. Depending on the content of that e-liquid, you may not have the same vaping experience as you would with a different vaping brand.