As an example. Lets say I owned 10 SOL. I placed a limit order to sell 6 SOL at a target price and this order is pending. Matcha then allowed me to place an additional limit order to sell 10 SOL at a target price. It should not have allowed me to place my second order of 10 SOL because I should only have 4 SOL available for using due to my first pending limit order.