menthod is calling multiple times

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C#

WCF

C#4.0

ASP.NET4

Hi All,
while I change or modify something in data access layer, I am getting below mentioned error.
1. Unable to copy file "C:\bin\Debug\ajaxservice.Data.dll" to "bin\Debug\ajaxservice.Data.dll". The process cannot access the file 'bin\Debug\ajaxservice.Data.dll' because it is being used by another process. ajaxservice.Services
2. Unable to copy file "C:\bin\Debug\ajaxservice.Business.dll" to "bin\Debug\ajaxservice.Business.dll". The process cannot access the file 'bin\Debug\ajaxservice.Business.dll' because it is being used by another process. ajaxservice.Services
After I restarting the system the error will not be again but I am getting method calling twice problem.
(Actually I am calling some WCF method from java script and some directly from C#. The menthod is calling multiple times whenever calling from java script. If I call from C#, the same methods working fine. Please help me how to fix this.)
var service = new Hotal.Services.IMenuSearchService();
service.FindRestaurant(City, Area, onRestaurantSeachSuccess, onRestaurantSeachFailed, null);

the below method only calling twice:

public IEnumerable<data.newrestaurantheader> FindRestaurant(string City, string Area)
        {
            Business.Menu menu = new Business.Menu();            
            return menu.FindRestaurant(City, Area);
        }


 public IEnumerable<data.newrestaurantheader> FindRestaurant(string City, string Area)
        {
            // LinQ query here

        }