Have you talked to a doctor about this?  I have had similar experiences, but it has usually been related to medicine I take sometimes (suppositories - yuck!).  My doctor has asked me about it before, so it definitely could be something IBD-related - so I think it would be a good idea to get a professional opinion! 

Good luck!

I think I have a solution.

I've had this problem since I was a little kid, and I just recently figured out what it was. I always had to return a couple hours later to wipe a second time, no matter how well I did the first time.

What worked for me (and I'm still testing this out) is to NOT try to squeeze every last bit of poop out. (This may sound graphic, so hold your mouths shut) The thing you should try is to squeeze out the poop until it plops violently into the toilet. Then STOP. Don't try to squeeze out anymore. If you attempt to get every last bit of poo out, you will end up leaving a small bit just on the inside of your anus, which will inevitably leak out. Holding back the rest of the crap will feel odd at first, but the feeling will go away in a few minutes and you will feel much better than if you had tried to squeeze everything out.

This may not be the same for all people, but it seemed to work for me, so test it out and report your findings.