James Wade and Robert Thornton made history as both players threw nine-dart finishes in their second-round match at the World Grand Prix in Dublin.
It is the first time that two players have completed perfect legs in the same competitive match.
Previously, only Brendan Dolan had hit a nine-darter in the double-start format, while Phil Taylor hit two in the 2010 Premier League final.
Ironically, Wade was the opponent on both occasions.
Wade, from Aldershot, beat Scotland's Thornton 3-2 to reach the quarter-finals, while Taylor, Kevin Painter and Gary Anderson also made it through to the last eight.
Thornton competed in the event despite the death of his mother last week, and had flown from Scotland to Dublin on Wednesday afternoon after attending her funeral earlier in the day.
"I can only congratulate Robert for what he's achieved there," said Wade.
"I'm really happy that I won, but to play Robert in that situation was so hard. I got a little bit excited with my nine-darter, and for Robert to do one as well was great.
"There was no nice way to play Robert with what he's gone through, and for him to do what he's done shows that there's nobody with any bigger heart than him."
In the double-start format players have to throw a double to begin the leg and a double to check out.
|1984: John Lowe v Keith Deller - first televised nine-dart finish|
|1990: Paul Lim v Jack McKenna - first at the BDO World Championship|
|2009: Raymond van Barneveld v Jelle Klaasen - first at the PDC World Championship|
|2010: Phil Taylor v James Wade - first to hit two nine-dart finishes in one match|
|2011: Adrian Lewis v Gary Anderson - first in a World Championship final|
|2011: Brendan Dolan v James Wade - first in the double-start format|
|2014: James Wade v Robert Thornton - first match in which both players have hit a nine-dart finish|