yes we can have that. in order to invoke the method of the 
same name we use base keyword before the method name. 

if the method in the base class is virtual, which is the 
case in most of the abstract classes we actually override 
the method in the derived class. 

it is therefore not a constraint in any way.

yes we can have the method in drived class with the same 
name which is there in the base class, But the condition is 
both should have diffrent parameters.....that's it.

It is possible to hide the base class method with the 
derived class without using Virtual in base class and 
Override keyword in subclass.there are some condition where 
we have to redefine any method in derived class same name 
in base class now question arise how can we hide the method 
anwer is simple and logical we use the modifier NEW which 
tell the compiler that derived class method "hides the base 
class method. There are some example:
Class baseclass
{
    Public void display()
    {
        console.writeline("base method");
    }
} 
class derived : baseclass
{
    public new void display()
    {
         console.writeline("dervied mthod");
     }
} 
class test
{
     public static void main()
    {
        derived d=new derivedclass();
        d.display();
    }
}

have a look at this link.

http://msdn2.microsoft.com/en-us/library/6fawty39
(VS.80).aspx

In C#, derived classes can contain methods with the same
name as base class methods.

    *

      The base class method must be defined virtual.
    *

      If the method in the derived class is not preceded by
new or override keywords, the compiler will issue a warning
and the method will behave as if the new keyword were present.
    *

      If the method in the derived class is preceded with
the new keyword, the method is defined as being independent
of the method in the base class.
    *

      If the method in the derived class is preceded with
the override keyword, objects of the derived class will call
that method instead of the base class method.
    *

      The base class method can be called from within the
derived class using the base keyword.
    *

      The override, virtual, and new keywords can also be
applied to properties, indexers, and events.

YES its posiible to have a method with same name in the 
derived class provide with
1. base class method should be hided by removing virtual 
keyword.
2.use new keyword in derived class instead of override.