To be fair, in proportion to the prison population and annual releases numbers it's not that common.
However with the recent increase in releases under the short sentence scheme, the number of people being released has jumped and therefore the errors have also arisen in part because of confusion over sentence calculations.
The problem for HMPPS, MOJ and the government is that prison is grossly underfunded, staff are frequently poorly trained and badly managed, morale is on the floor and retention rates are appalling.
This being so high profile will do nothing to help change much except beat a few prison officers over the head for letting them leave despite umpteen layers of managers having responsibility for the process of calculating sentences and checking releases before the prisoners get to the gates.
And now I better NC.....