Potty Draining

Yes, I'm attempting to potty train the twins, but so far, it's only draining me of all of my patience and energy.
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The boys just plain refuse to put on undies. I have to hide the diapers or they'll bug me to death whining and crying to have them on. Patrick decided he wasn't going to wait for me the other day (before I figured out the hiding thing) so he diapered himself. He did a fine job, too. I think I'll let them take care of their own diapers from now on. Except for the poopy ones. My carpet can't handle that.
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Even with their favorite character undies on (Cars, Buzz Lightyear, Kung Fu Panda, Chicken Little) they still treat them just like diapers. When they have an accident (seven today alone), they are responsible for tossing the wet clothes down the laundry chute and finding new undies and pants to wear all by themselves. This may sound a little harsh, but I know they can go on the potty. We've had several "Practice Days" before the holidays and they did great - dry all day long. They're just being pig-headed now that I'm ready to train for real.
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Will they eventually get tired of the mess and start to go in the potty? We have incentives: stickers for #1, a party with cupcakes for the first time going #2 (still hasn't happened), candy dispensers for a full day of being dry... you name it. What are we doing wrong???