I deleted a tab from an existing document type and then renamed the alias of one of the fields on the document type and now I am receiving the following error message:

 2016-04-18 08:42:55,234 [P8584/D7/T1] ERROR Umbraco.Core.UmbracoApplicationBase - An unhandled exception occurred
System.ArgumentException: An item with the same key has already been added.
   at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)
   at System.Collections.ObjectModel.KeyedCollection`2.AddKey(TKey key, TItem item)
   at Umbraco.Core.Models.PropertyGroupCollection.InsertItem(Int32 index, PropertyGroup item)
   at Umbraco.Core.Models.PropertyGroupCollection.Add(PropertyGroup item)
   at Umbraco.Core.EnumerableExtensions.ForEach[TItem](IEnumerable`1 items, Action`1 action)
   at Umbraco.Core.Models.PropertyGroupCollection.Reset(IEnumerable`1 groups)
   at Umbraco.Core.Persistence.Repositories.ContentTypeBaseRepository`1.ContentTypeQueryMapper.MapGroupsAndProperties(Int32[] contentTypeIds, Database db, ISqlSyntaxProvider sqlSyntax, IDictionary`2& allPropertyTypeCollection, IDictionary`2& allPropertyGroupCollection)
   at Umbraco.Core.Persistence.Repositories.ContentTypeBaseRepository`1.ContentTypeQueryMapper.MapContentTypeChildren[TRepo,TId](IContentTypeComposition[] contentTypes, Database db, ISqlSyntaxProvider sqlSyntax, TRepo contentTypeRepository, IDictionary`2 allParentContentTypeIds)
   at Umbraco.Core.Persistence.Repositories.ContentTypeBaseRepository`1.ContentTypeQueryMapper.GetContentTypes[TRepo,TId](TId[] contentTypeIds, Database db, ISqlSyntaxProvider sqlSyntax, TRepo contentTypeRepository, ITemplateRepository templateRepository)
   at Umbraco.Core.Persistence.Repositories.ContentTypeRepository.PerformGetAll(Int32[] ids)
   at Umbraco.Core.Persistence.Repositories.RepositoryBase`2.GetAll(TId[] ids)
   at Umbraco.Core.Persistence.Repositories.ContentRepository.ProcessQuery(Sql sql)
   at Umbraco.Core.Persistence.Repositories.VersionableRepositoryBase`2.GetPagedResultsByQuery[TDto,TContentBase](IQuery`1 query, Int64 pageIndex, Int32 pageSize, Int64& totalRecords, Tuple`2 nodeIdSelect, Func`2 processQuery, String orderBy, Direction orderDirection, Func`1 defaultFilter)
   at Umbraco.Core.Persistence.Repositories.ContentRepository.GetPagedResultsByQuery(IQuery`1 query, Int64 pageIndex, Int32 pageSize, Int64& totalRecords, String orderBy, Direction orderDirection, String filter)
   at Umbraco.Core.Services.ContentService.GetPagedDescendants(Int32 id, Int64 pageIndex, Int32 pageSize, Int64& totalChildren, String orderBy, Direction orderDirection, String filter)
   at UmbracoExamine.UmbracoContentIndexer.PerformIndexAll(String type)
   at UmbracoExamine.BaseUmbracoIndexer.PerformIndexRebuild()
   at Examine.ExamineManager._RebuildIndex() in x:\Projects\Examine\Examine\Projects\Examine\ExamineManager.cs:line 240
   at Umbraco.Web.WebBootManager.<InitializeResolvers>b__c()
   at Umbraco.Core.Sync.DatabaseServerMessenger.Initialize()
   at Umbraco.Core.Sync.DatabaseServerMessenger.Boot()
   at Umbraco.Core.CoreBootManager.<Complete>b__8(IApplicationEventHandler x)
   at Umbraco.Core.EnumerableExtensions.ForEach[TItem](IEnumerable`1 items, Action`1 action)
   at Umbraco.Core.CoreBootManager.Complete(Action`1 afterComplete)
   at Umbraco.Web.WebBootManager.Complete(Action`1 afterComplete)
   at Umbraco.Core.UmbracoApplicationBase.StartApplication(Object sender, EventArgs e)

For the life of me I am unable to find out what the issue is, I can see it is something to do with the property data but cannot see where the actual issue lies.

Any ideas??