#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "(?ms)^(.{14}).*\s^(?=.{0,14}^\1.*)"
Local $sString = "09/07/21,10:00,11.a,100,11.6,5,13,330,6.0,2.8,1014.0,33.0,23.8,44,5,11.6,11.6,0.0,75,0.00,579.70,11.0,444,0.0,320,0.0,31.7,11.4,13.6" & @CRLF & _
"09/07/21,10:00,11.c,100,11.6,6,13,330,6.0,2.8,1014.0,33.0,23.8,44,5,11.6,11.6,0.0,75,0.00,579.70,11.0,444,0.0,320,0.0,31.7,11.4,13.6" & @CRLF & _
"09/07/21,10:00,11.b,100,11.6,6,13,330,6.0,2.8,1014.0,33.0,23.8,44,5,11.6,11.6,0.0,75,0.00,579.70,11.0,444,0.0,320,0.0,31.7,11.4,13.6" & @CRLF & _
"09/07/21,10:10,11.7,100,11.7,6,15,337,1.2,3.3,1013.9,33.5,23.9,44,4,11.7,11.7,0.0,82,0.00,579.70,11.1,465,0.0,330,0.0,32.2,11.4,13.8" & @CRLF & _
"09/07/21,10:10,11.7,100,11.7,6,15,337,1.2,3.3,1013.9,33.5,23.9,44,4,11.7,11.7,0.0,82,0.00,579.70,11.0,465,0.0,330,0.0,32.2,11.4,13.8" & @CRLF & _
"09/07/21,10:20,11.9,100,11.9,6,11,337,3.0,3.8,1013.9,34.0,24.0,44,6,11.9,11.9,1.0,198,0.00,579.70,11.2,484,0.0,354,0.0,32.7,11.5,14.1" & @CRLF & _
"09/07/21,10:20,11.9,100,11.9,6,11,336,3.0,3.8,1013.9,34.0,24.0,44,6,11.9,11.9,1.0,198,0.00,579.70,11.3,484,0.0,354,0.0,32.7,11.6,14.1" & @CRLF & _
"09/07/21,10:30,12.1,100,12.1,5,13,345,1.8,4.1,1013.7,34.3,24.0,45,9,12.1,12.1,1.0,177,0.00,579.70,11.7,502,0.0,355,0.0,33.0,12.0,14.4" & @CRLF & _
"09/07/21,10:30,12.1,100,12.1,6,13,344,1.8,4.1,1013.7,34.3,24.0,45,9,12.1,12.1,1.0,182,0.00,579.70,11.7,502,0.0,337,0.0,33.0,11.9,14.4" & @CRLF & _
"07/07/21,16:50,14.4,40,1.0,2,2,237,0.0,0.0,953.8,0.0,26.0,32,1,14.4,14.4,0.0,14,0.00,579.70,12.3,4,0.1,237,0.0,0.0,13.9,12.5" & @CRLF & _
"07/07/21,16:50,14.4,40,1.0,2,2,237,0.0,0.0,953.8,0.0,26.0,32,1,14.4,14.4,0.0,14,0.00,579.70,12.3,4,0.1,237,0.0,0.0,13.9,12.5" & @CRLF & _
"07/07/21,17:00,13.4,43,1.1,0,1,237,0.0,0.0,953.7,0.0,25.7,33,0,13.4,13.4,0.0,7,0.00,579.70,11.5,0,0.3,237,0.0,0.0,13.1,11.5" & @CRLF & _
"07/07/21,17:00,13.4,43,1.1,0,1,237,0.0,0.0,953.7,0.0,25.7,33,0,13.4,13.4,0.0,7,0.00,579.70,11.5,0,0.3,237,0.0,0.0,13.1,11.5" & @CRLF & _
"07/07/21,17:10,12.7,46,1.4,0,0,0,0.0,0.0,953.9,0.0,25.3,32,0,12.7,12.7,0.0,2,0.00,579.70,10.9,0,0.4,237,0.0,0.0,12.5,10.9" & @CRLF & _
"07/07/21,17:20,11.3,51,1.5,0,0,0,0.0,0.0,953.8,0.0,25.1,33,0,11.3,11.3,0.0,0,0.00,579.70,9.5,0,0.5,237,0.0,0.0,11.2,9.5" & @CRLF & _
"07/07/21,17:20,11.3,51,1.5,0,0,0,0.0,0.0,953.8,0.0,25.1,33,0,11.3,11.3,0.0,0,0.00,579.70,9.5,0,0.5,237,0.0,0.0,11.2,9.5" & @CRLF & _
"07/07/21,17:30,10.3,55,1.6,0,0,0,0.0,0.0,954.0,0.0,24.8,33,0,10.3,10.3,0.0,0,0.00,579.70,8.6,0,0.5,237,0.0,0.0,10.3,8.6" & @CRLF & _
"07/07/21,17:30,10.3,55,1.6,0,0,0,0.0,0.0,954.0,0.0,24.8,33,0,10.3,10.3,0.0,0,0.00,579.70,8.6,0,0.5,237,0.0,0.0,10.3,8.6" & @CRLF & _
""
Local $sSubst = ""
Local $sResult = StringRegExpReplace($sString, $sRegex, $sSubst)
MsgBox($MB_SYSTEMMODAL, "Result", $sResult)
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for AutoIt, please visit: https://www.autoitscript.com/autoit3/docs/functions/StringRegExp.htm