example.rb

module MyModule
  def some_method
    super
  rescue SystemStackError => e
    puts "you're including MyModule more than once"
  end
end

class MyBaseClass; end

class MySubClass < MyBaseClass;
  include MyModule
end

MyBaseClass.class_eval { include MyModule }

MySubClass.new.some_method

ruby 1.9 output

$ ruby example_spec.rb 
you're including MyModule more than once