Absolutely they can. Just look at the Greek Magical Papyri. There are spells that call on Greek, Egyptian, and Hebrew gods, spirits, and names all over in the PGM, often in the same ritual. The techniques therein are a synthesis of Greek, Egyptian, and Hebrew magical techniques.
For myself, I practice a lot of different kinds of magic some would say are incompatible with each other. I practice Solomonic magic, Graeco-Egyptian sorcery, witchcraft and folk magic, and others. I even blend techniques from all these sources into the same ritual. I've certainly seen results many times from this.