#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "(?ms)^(([^,]+).*?)^\2,[^\n]*(\n|$)"
Local $sString = "100.100.100.1,"10","2019-02-12 16:20:23"" & @CRLF & _
"100.100.100.1,"10","2019-02-12 16:20:28"" & @CRLF & _
"100.100.100.2,"10","2019-02-12 16:20:26"" & @CRLF & _
"100.100.100.2,"10","2019-02-12 16:20:27""
Local $sSubst = "$1"
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