+1 - And crazy to leave a bag at ORD for that long even if they would do it for you, which they won't.
Whether OP is charged a second fee depends on how he is ticketed. If this is China-PIT with a connection at ORD, he won't be charged the second fee. But, the 20-hour break at ORD makes this sounds like a stopover, in which case it's a second fee.