Is it Possible to have twins and the doctors not see it?

I am about 23 weeks pregnant and before i even got pregnant i was read the Tarot cards that said i was going to get pregnant with a "minor male" meaning it was gonna have a winky :) less than a month later, voila! I'm pregnant and they say I'm having a boy. I got my cards read again, and they say i'm going to have twins. I'm skeptical of this... but the thought of it is exciting. I've had two ultra sounds in the past and only "saw one". my little one hates the camera so he dodges and spinsand summersaults to get away from the probe so he can barely be seen. This morning i was admitted into the emergency room and the doctor there had the probe for U/S on my far far right hand side. Almost hitting my hip bone. and the strangest thing was seen... There was an exact mirrored circle of my little boys head. almost looking like that "inifinate sign" or an eight on its side. and he jokingly asked, is that a second head i see? but because we couldnt SEE the rest of it, we shook it off as a joke. I know it wasnt my bladder because the bladder is shaped like the textbook drawings of Cells, you know with the squiggly lining? the second round circle looked exactly like my baby's head... just facing another direction, and this is the first time ive seen it in any of my ultra sounds. Is possible that there is another little one hiding fromthe world behind my little boy? if so, would be identical or unidentical?