I can't explain about the 600,000 shares you bought. Perhaps your broker did a match trade in house. Don't know who your broker is, but you might call and ask them.
The 1 share fill? I've seen that a couple of times. Perhaps some disgruntled trader sold you one share out of meanness. Or perhaps as a joke.
May I ask who your broker is and what you paid for the 600,000 shares? If they were at the ask, I would be curious as to why that trade was not shown.
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