Police charged 28-year-old Australian Brenton Tarrant with a single, representative count of murder after 50 people were killed in Friday’s shootings at two mosques in the quiet city.
But on Thursday police said they made an error on the charging sheet prepared for Mr Tarrant’s first court appearance the day after the attack.
In a statement, they said officers have spoken with the person incorrectly named on the document and have apologised, and that they would change the charge sheet.
A gunman killed 50 people after opening fire at two mosques in Christchurch during Friday prayers on 15 March.
The attacks began at the Al Noor mosque at about 1.40pm, where 42 people were killed.
The gunman, who police believe acted alone, then drove about three miles across town where he attacked the Linwood mosque, killing seven more people. One person also died later in a hospital.
Among the victims were children, including three-year-old Mucad Ibrahim, four-year-old Abdullahi Dirie and 14-year-old Sayyad Milne.
At least six funerals took place on Wednesday, including for Cashmere High School student Sayyad and a youth football coach.
New Zealand prime minister Jacinda Ardern has been praised for her response to the shootings.
Less than a week after the attack, the country has announced that all semi-automatic, military-style weapons have been banned.
Unveiling details of the plan agreed by cabinet earlier this week, Ms Ardern said assault rifles and “related parts used to convert these guns (such as bump stocks) are also being banned, along with all high-capacity magazines”.
The prime minister said an amnesty would be issued for New Zealanders who own the types of weapons being banned, and that a government buy-back scheme could cost “anywhere from $100m to $200m (£52m-£104m)".