I know what you are thinking, but pulling from the back of my mind, I cannot recall ever DK'ing a trade before the open the next day while at the same time inputing the As Of trade into Act to compare a DK trade. I would let it sit in my error account until I figured it out.
Surfkast, my good friend is rocking the apple cart for as you said a 10,000 share out of sequence trade.
I can't tell you how many times I bolted out the door at the bell, only to come back hours later to input phoned orders, or A/O the next day non comps, and yes, I had notes as to whom and when, called them the next am just to let them know I was going to A/O and ACT my side so the client account can settle pursuant to T+, if they did not call me first.
I really think this was an out of sequence lazy trader.