only perform pinning functions on first/last pin

bot.rb

@@ -35,7 +35,7 @@ bot.reaction_add do |event|
   end
 
   if(event.emoji.name == PIN_EMOJI)
-    event.message.pin
+    event.message.pin unless event.message.reactions.include? PIN_EMOJI
   end
 
   nil # `event` is of type Respondable, so the return line of the block needs to be nil to prevent the bot sending something in the chhannel the reaction occured.
@@ -43,7 +43,7 @@ end
 
 bot.reaction_remove do |event|
   next unless event.emoji.name == PIN_EMOJI
-  event.message.unpin
+  event.message.unpin unless event.message.reactions.include? PIN_EMOJI
   nil
 end