WIW: Ard Einin, Marino Avenue East, Killiney, Co Dublin

Just saw this on the Property Price Register which must have been sold off-market.
There are two asterisks after the figure ('denotes not full market price) whatever that means ?

26/07/2013 €1,650,000.00 ** Ard Einin, Killiney

A lot of history in this house including used by Michael Collins and owned by descendants of Daniel O’Connell
Previously brought to auction in May 2003 asking 2.25m but failed to sell and was put on privately for 3.25m (strange logic)
No record of it being sold after that but likely that it was

Paper refers to a 1 acre house and looks about 3,000 sq ft.