diff --git a/src/MappingExtensions.cs b/src/MappingExtensions.cs
index 259a509..fcc31da 100644
--- a/src/MappingExtensions.cs
+++ b/src/MappingExtensions.cs
@@ -147,7 +147,7 @@ public static string GetConditionalSql(string conditionalsSql, string columnName
                     {
                         if (mappingConditional.SourceColumn.Type == typeof(string))
                         {
-                            conditionalValue = string.Join(",", conditionalValue.Split(new string[] { "," }, StringSplitOptions.RemoveEmptyEntries).Select(val => $"'{val}'"));
+                            conditionalValue = string.Join(",", conditionalValue.Split(new string[] { "," }, StringSplitOptions.RemoveEmptyEntries).Select(val => $"'{val.Trim()}'"));
                         }
                         conditionalsSql = string.Format(
                             "{0}[{1}] IN ({2}) and ",
@@ -164,7 +164,7 @@ public static string GetConditionalSql(string conditionalsSql, string columnName
                     {
                         if (mappingConditional.SourceColumn.Type == typeof(string))
                         {
-                            notInConditionalValue = string.Join(",", notInConditionalValue.Split(new string[] { "," }, StringSplitOptions.RemoveEmptyEntries).Select(val => $"'{val}'"));
+                            notInConditionalValue = string.Join(",", notInConditionalValue.Split(new string[] { "," }, StringSplitOptions.RemoveEmptyEntries).Select(val => $"'{val.Trim()}'"));
                         }
                         conditionalsSql = string.Format(
                             "{0}[{1}] NOT IN ({2}) and ",
diff --git a/src/SQLDestinationWriter.cs b/src/SQLDestinationWriter.cs
index 2d48578..d794138 100644
--- a/src/SQLDestinationWriter.cs
+++ b/src/SQLDestinationWriter.cs
@@ -160,7 +160,7 @@ protected virtual void Initialize()
         {
             List<SqlColumn> destColumns = new List<SqlColumn>();
             var columnMappings = Mapping.GetColumnMappings();
-            foreach (ColumnMapping columnMapping in columnMappings)
+            foreach (ColumnMapping columnMapping in columnMappings.DistinctBy(obj => obj.DestinationColumn.Name))
             {
                 destColumns.Add((SqlColumn)columnMapping.DestinationColumn);
             }
@@ -200,23 +200,15 @@ public virtual void Write(Dictionary<string, object> row)
             {
                 if (columnMapping.HasScriptWithValue || row.ContainsKey(columnMapping.SourceColumn.Name))
                 {
-                    switch (columnMapping.ScriptType)
+                    object dataToRow = columnMapping.ConvertInputValueToOutputValue(row[columnMapping.SourceColumn.Name]);
+
+                    if (columnMappings.Any(obj => obj.DestinationColumn.Name == columnMapping.DestinationColumn.Name && obj.GetId() != columnMapping.GetId()))
+                    {
+                        dataRow[columnMapping.DestinationColumn.Name] += dataToRow.ToString();
+                    }
+                    else
                     {
-                        case ScriptType.None:
-                            dataRow[columnMapping.DestinationColumn.Name] = columnMapping.ConvertInputToOutputFormat(row[columnMapping.SourceColumn.Name]);
-                            break;
-                        case ScriptType.Append:
-                            dataRow[columnMapping.DestinationColumn.Name] = columnMapping.ConvertInputToOutputFormat(row[columnMapping.SourceColumn.Name]) + columnMapping.ScriptValue;
-                            break;
-                        case ScriptType.Prepend:
-                            dataRow[columnMapping.DestinationColumn.Name] = columnMapping.ScriptValue + columnMapping.ConvertInputToOutputFormat(row[columnMapping.SourceColumn.Name]);
-                            break;
-                        case ScriptType.Constant:
-                            dataRow[columnMapping.DestinationColumn.Name] = columnMapping.GetScriptValue();
-                            break;
-                        case ScriptType.NewGuid:
-                            dataRow[columnMapping.DestinationColumn.Name] = columnMapping.GetScriptValue();
-                            break;
+                        dataRow[columnMapping.DestinationColumn.Name] = dataToRow;
                     }
                 }
                 else
@@ -425,7 +417,7 @@ public virtual void MoveDataToMainTable(SqlTransaction sqlTransaction, bool upda
             {
                 string sqlConditions = "";
                 string firstKey = "";
-                var columnMappings = Mapping.GetColumnMappings().Where(cm => cm.Active);
+                var columnMappings = Mapping.GetColumnMappings().Where(cm => cm.Active).DistinctBy(obj => obj.DestinationColumn.Name);
                 bool isPrimaryKeyColumnExists = columnMappings.IsKeyColumnExists();
 
                 foreach (ColumnMapping columnMapping in columnMappings)