Calling multiple dll imports with the same method name

I'm importing several unmanaged c++ DLL's into my project however the imported DLLs have the same method name which causes compiler issues. For example;

unsafe class Myclass
{
   [DllImport("myfirstdll.dll")]
   public static extern bool ReturnValidate(long* bignum);

   [DllImport("myseconddll.dll")]
   public static extern bool ReturnValidate(long* bignum);

   public Myclass
   {
      int anum = 123;
      long passednum = &anum;
      ReturnValidate(passsednum);
   }
}

Now what I'd like to do would be rename the method on import. Something like;

[DllImport("myseconddll.dll")]
public static extern bool ReturnValidate(long bignum) AS bool ReturnValidate2(long bignum);

Is this possible?