Merge pull request #170 from tuespetre/master

Fixed regression with sproc tests

Dapper NET40/SqlMapper.cs

@@ -4396,6 +4396,11 @@ protected void AddParameters(IDbCommand command, SqlMapper.Identity identity)
                 // The parameters were added to the command, but not the 
                 // DynamicParameters until now.
                 foreach (IDbDataParameter param in command.Parameters)
+                {
+                    // If someone makes a DynamicParameters with a template,
+                    // then explicitly adds a parameter of a matching name,
+                    // it will already exist in 'parameters'.
+                    if (!parameters.ContainsKey(param.ParameterName)) 
                     { 
                         parameters.Add(param.ParameterName, new ParamInfo
                         {
@@ -4408,6 +4413,7 @@ protected void AddParameters(IDbCommand command, SqlMapper.Identity identity)
                             Value = param.Value
                         });
                     }
+                }
 
                 // Now that the parameters are added to the command, let's place our output callbacks
                 var tmp = outputCallbacks;