typo: Double word "this" (#36273)

src/Common/src/CoreLib/System/Globalization/EastAsianLunisolarCalendar.cs

@@ -619,7 +619,7 @@ public override bool IsLeapMonth(int year, int month, int era)
 
         /// <summary>
         /// Returns  the leap month in a calendar year of the specified era. This method returns 0
-        /// if this this year is not a leap year.
+        /// if this year is not a leap year.
         /// </summary>
         public override int GetLeapMonth(int year, int era)
         {

src/System.Configuration.ConfigurationManager/src/System/Configuration/ConfigurationElementProperty.cs

@@ -4,7 +4,7 @@
 
 namespace System.Configuration
 {
-    //  Although in Whidbey this class contain just one property, but we still do this this way, 
+    // Although in Whidbey this class contains just one property, but we still do it this way, 
     // instead of exposing a Validator property in ConfigurationElement, because if we need 
     // another property in the future we'll expand this ElementProperty class rather than adding a 
     // new overridable on ConfigurationElement
@@ -19,4 +19,4 @@ public ConfigurationElementProperty(ConfigurationValidatorBase validator)
 
         public ConfigurationValidatorBase Validator { get; }
     }
-}
+}

src/System.Net.Http/tests/FunctionalTests/HttpClientHandlerTest.cs

@@ -778,7 +778,7 @@ public async Task PostAsync_ManyDifferentRequestHeaders_SentCorrectly()
                 // System.InvalidCastException: "Unable to cast object of type 'System.Object[]' to type 'System.Net.Http.WinHttpRequestState'"
                 // This appears to be due to adding the Expect: 100-continue header, which causes winhttp
                 // to fail with a "The parameter is incorrect" error, which in turn causes the request to
-                // be torn down, and in doing so, we this this during disposal of the SafeWinHttpHandle.
+                // be torn down, and in doing so, we handle this during disposal of the SafeWinHttpHandle.
                 return;
             }