diff --git a/lib/poise/helpers/resource_subclass.rb b/lib/poise/helpers/resource_subclass.rb
index <HASH>..<HASH> 100644
--- a/lib/poise/helpers/resource_subclass.rb
+++ b/lib/poise/helpers/resource_subclass.rb
@@ -57,6 +57,7 @@ module Poise
           else
             subclass_resource_equivalents << superclass_resource_name
           end
+          subclass_resource_equivalents.uniq!
         end
 
         # An array of names for the resources this class is equivalent to for
Uniq the equivalents in case this is called more than once.