Error multiple properties with the same name in LINQ query

I am working on Linq query and I am getting error on functionNavigation_b.Title column. I am using LinqPad to test my queries initially,

Error

An anonymous type cannot have multiple properties with the same name

LINQ Query

from functionNavigation in Sys_Nav_Functions
join functionHierarchy in Sys_Nav_FunctionHierarchies on functionNavigation.Function_ID equals functionHierarchy.Function_ID 
join functionNavigation_b in Sys_Nav_Functions on functionHierarchy.Parent_Function_ID equals functionNavigation_b.Function_ID
 select new {
              functionNavigation.Function_ID, 
              functionNavigation.Title, 
              functionNavigation.Hierarchy_Level,
              functionHierarchy.Parent_Function_ID, 
              functionNavigation_b.Title 
            }