Sharpen is the most likely ppo to cause problems with soybean emergence, seems like at the 1 oz rate the residual is pretty short too.  Since you have not seen problems yet you might be able to increase your ppo at planting before you have a complete kill on your soybeans. 

How much valor do you use on your earlier pass? What is your pH? ppo burn seems worse on pH above 7 or ground that has been limed recently.  We use valor on both passes.