What this sounds like to me is that when you double dose, or push the envelope further, you're so far from the shores of your ego that the experience gets seemingly "hijacked" by an alien otherness. There's much debate of course whether these entities are actually an "other" or just a more alienated manifestation of our psyche (or the collective psyche). It would make sense to me that after stretching your filter a few times you're opening the experience up to entire pantheons of new manifestations of spirt, or intelligence, or whatever you want to call it.
Thinking about psychedelic experiences in general, to the extent that journey feels connected to a personal sense of meaning I think is a reliable marker that while you are out exploring the waters, you're still in site of the shoreline. When that is lost and it suddenly feels you are caught up the agenda of some other intelligence, well, now you're heading out into uncharted waters.
As for what's out there or why, well, that's why we're all here I suppose.
I've experienced this twice with just the spice (smoking it in a similar manner as you've described), but the most intense experience I had with this was when I ate 5 grams of shrooms, then smoked spice midway through the trip. This actually resulted in a short (35 minute) psychotic break.
"We're all in this together, by ourselves." --Lily Tomlin