That orphan is part of a larger order, it only shows 1 as that...

That orphan is part of a larger order, it only shows 1 as that what was remaining from the larger order that still needed to be executed.

Eg: market depth

Buys :
150,000 @0.995

Sells:
300,000 @ 0.995

Someone then comes along and places a 299,999 buy at $1.000

New depth:
Buys :
299,999 @ 1.000
150,000 @0.995

Sells:
300,000 @ 0.995

Auction executes a sell of 299,999 from the 300,000 order 1 unit still remains but as the sell was willing to sell at 0.995 that remaining one gets sold into the 0.995 line. Then overall all 300,000 units get sold at 0.995.

Trades of the day would look like this
16:10:01 - 1 - $0.995 - $1.00
16:10:01 - 299,999 - $0.995 - $298,499.01

Looks like the 1 unit is an orphan, but it isn't as the 1 comes from the 150,000 order at 0.995 line. That order now looks like 149,999 @ 0.995