Error when mapping same value with AutoMapper

I've got this code which fails: ``` internal class Program { private static void Main() { Mapper.CreateMap<SourceFoo, TargetFoo>(); Mapper.CreateMap<string, Stuff>() .ForMember(dest => dest.Value, opt => opt.MapFrom(src => src)) .ForMember(dest => dest.IgnoreMe, opt => opt.Ignore()); var source = new SourceFoo { Stuff = "a", Stuff2 = "a" }; var target = new TargetFoo { Stuff = new Stuff(), Stuff2 = new Stuff() }; Mapper.Map(source, target); Console.WriteLine(target.Stuff.Value); Console.WriteLine(target.Stuff2.Value); Console.ReadLine(); } } public class SourceFoo { public string Stuff { get; set; } public string Stuff2 { get; set; } } public class TargetFoo { public Stuff Stuff { get; set; } public Stuff Stuff2 { get; set; } } public class Stuff { public string Value { get; set; } public bool IgnoreMe { get; set; } } ``` When Stuff/Stuff2 has the same value I get this exception: An item with the same key has already been added. If they have different values everything works. I use AutoMapper 2.2.0. Have I done something wrong or is it a bug? How can I solve it?