Slapper.AutoMapper returns only single result from list of objects

I've two POCO-s. A and B.

public class A{
    [Slapper.AutoMapper.Id]
    public int Id { get; set; }
    public B BType { get; set; }
    // Rest of the fields
}

public class B{
    [Slapper.AutoMapper.Id]
    public int Id { get; set; }
    public string Name {get;set;}
}

T-SQL Stored Procedure result:

ID      B_Id    B_Name
1       1       B1
2       2       B2

My code to get List with Dapper is:

List<A> aList = new List<A>();
            using (IDbConnection connection = new SqlConnection(GlobalConfig.ConnectionString()))
            {
                var p = new DynamicParameters();
                p.Add("@Id", someId);
                // Here debug shows me 2 correct objects inside of var list
                var list = connection.Query<dynamic>("[spApp_getBlaBlaByID]", p, commandType: CommandType.StoredProcedure);

                // After casting I got only 1
                aList =(Slapper.AutoMapper.MapDynamic<A>(list) as IEnumerable<A>).ToList();

            }
            return aList; // Debugging shows only 1 one of the objects

So, what is wrong with my code? Please help to find mistake. P.S. I came to C# from Java. Maybe in C# world Slapper.Automapper is not in trend anymore. What is flexible and modern solution to map POCO-s with DAPPER?