I get the following error when I run k kestrel:

```
System.ArgumentException: An element with the same key already exists in the dictionary.
  at System.Collections.Generic.Dictionary`2[TKey,TValue].Add (System.Collections.Generic.TKey key, System.Collections.Generic.TValue value) [0x00000] in <filename unknown>:0 
  at System.Linq.Enumerable.ToDictionary[DictionaryEntry,String,String] (IEnumerable`1 source, System.Func`2 keySelector, System.Func`2 elementSelector, IEqualityComparer`1 comparer) [0x00000] in <filename unknown>:0 
  at Microsoft.Framework.ConfigurationModel.EnvironmentVariablesConfigurationSource.Load (IDictionary envVariables) [0x00000] in <filename unknown>:0 
  at Microsoft.Framework.ConfigurationModel.EnvironmentVariablesConfigurationSource.Load () [0x00000] in <filename unknown>:0 
  at Microsoft.Framework.ConfigurationModel.Configuration.Add (IConfigurationSource configurationSource) [0x00000] in <filename unknown>:0 
  at Microsoft.Framework.ConfigurationModel.ConfigurationExtensions.AddEnvironmentVariables (IConfigurationSourceContainer configuration) [0x00000] in <filename unknown>:0 
  at Microsoft.AspNet.Hosting.Program.Main (System.String[] args) [0x00000] in <filename unknown>:0 
  at (wrapper managed-to-native) System.Reflection.MonoMethod:InternalInvoke (System.Reflection.MonoMethod,object,object[],System.Exception&)
  at System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00000] in <filename unknown>:0 

```

It points to a duplicate environment variable but I just don't seem to be able to find it.

Does anyone know what the duplicate could be? It may be related to Linux as I had to reinstall that...