Visual Studio multiline reg-exp to remove duplicate using statements

I need regular expression to remove duplicate using statements.

using NS.SN.Services.Common;
using NS.SN.Data.BaseRegistry;
using NS.SN.Data.DataContracts.Registry;
using NS.SN.Services.Common; <-- this one must go
using NS.SN.Services.DataContracts;
using System;
using System.Collections.Generic;
using System.Transactions;
using CodeEnums = NS.SN.Data.DataContracts.Enums.CodeEnums;
using System.Linq;

Problem is that this reg-开发者_JAVA百科exp does not work because ([.:b]*\n)* matches only first new-line char. Can I fix this reg-exp?

{:b*using:bNS.SN.Services.Common;([.:b]*\n)*}using:bNS.SN.\Services.\Common;:b*\n

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Use this as "Find what":

{:b*using:bNS\.SN\.Services\.Common;(.*\n)*}using:bNS\.SN\.Services\.Common;:b*\n

and this as "Replace with":

\1

UPDATE:
I completely missed the dot inside the character group:
[.:b]* will match the dot or the colon or the letter b, because it is inside a character class! What you meant is (.|:b)*, where the :b is redundant, because it is contained inside "any character" (.), so it simply should be .*. See the updated regex above.