I hope I understand your question, but it should not be possible for them to "meet" or to trade. If two such orders were submitted, and there were no other orde

I hope I understand your question, but it should not be possible for them to "meet" or to trade. If two such orders were submitted, and there were no other orders in the book, then these orders would be both passive. IE. They would both sit there with the best bid at 10 and the best ask at 10.5. If these orders were the other way around (buy at 10.5 and sell at 10) then what would happen would depend on which order was submitted first. If the buy was submitted first, then the sell order would be aggressive. This would result in a trade at a price of 10.5 (the price of the passive order) which would be a better price for the sell order. If the sell order was first, then the trade would happen at 10 which would be a better price for the sell order.