According to your description, I would suggest you try checking out the links for details :

How to prevent ASMX (web service) replay attacks

http://forums.asp.net/t/1644752.aspx

http://msdn.microsoft.com/en-us/library/ff648635.aspx

How To: Enable Token Replay Detection

http://msdn.microsoft.com/en-us/library/jj161103(v=vs.110).aspx

If you have any questions please do not hesitate to contact me.