I have one stoma but the lower part of my bowel is attached at the side and while mostly I'm not aware of it sometimes when my bag is overfill at night with gas or output it will push down the "downpipe". Then I can pass gas or worse in the normal way or when i change my bag output will ooze up from the second hole. The longer I've had the stoma the less this happens but it does still occur. I think the type of stoma is called abcarian (?????) but its been a while since I got this one so could be wrong.