Roberto,
Personally i was confused too when i first tried to grasp this concept of Buddhas having multiple emanations, likely due to my limited Dharma knowledge.
However, as i looked around the world today with all its technological advancement, i found a close analogy that made me understand this concept or phenomenon. I hope my "silly" analogy can help you understand better.
I found it to be very real when i watched a documentary on tv about the internet and virtual reality gaming culture in our society today. Some real hardcore virtual reality gamers actually lives out an alter ego life in those virtual world of their CHOICE and what is even more real is that some actually immerse their life and soul into those virtual worlds in cyber space as their customized "AVATARS" .
Some of these hardcore gamers even become professionals in such worlds that they can generate income for the real world we live in. Some become so obsessed that they "EMANATE" (LOL) MULTIPLE Avatars that exists simultaneously in one "world" (game) or in MULTIPLE worlds (games) !
So Roberto , if a "normal" hardcore computer gamer who has a mind capacity, as any of us smucks out here in samsara, can create an Avatar OR multiples of them and "live" those "lives" simultaneously.................
Imagine what a BUDDHA mind can do ! In fact there is some scientist who believe that we could possibly be living this samsaric life in a form a " virtual reality " created by all our COLLECTIVE CONSCIOUSNESS !
I hope my 2 cents worth made sense, or at least it made you LOL. Cheers !