prevent users from being able to both upvote and downvote

app/assets/javascripts/awards_handler.coffee

@@ -22,8 +22,19 @@ class @AwardsHandler
     emoji = $(this)
       .find(".icon")
       .data "emoji"
+
+    if emoji is "thumbsup" and awards_handler.didUserClickEmoji $(this), "thumbsdown"
+      awards_handler.decrementCounter "thumbsdown"
+
+    else if emoji is "thumbsdown" and awards_handler.didUserClickEmoji $(this), "thumbsup"
+      awards_handler.decrementCounter "thumbsup"
+
     awards_handler.addAward emoji
+  didUserClickEmoji: (that, emoji) ->
+    if $(that).siblings("button:has([data-emoji=#{emoji}])").attr("data-original-title")
+      $(that).siblings("button:has([data-emoji=#{emoji}])").attr("data-original-title").indexOf('me') > -1
+
   showEmojiMenu: ->
     if $(".emoji-menu").length
       if $(".emoji-menu").is ".is-visible"
@@ -105,7 +116,7 @@ class @AwardsHandler
     if origTitle
       authors = origTitle.split(', ')
     authors.push("me")
-    award_block.attr("title", authors.join(", "))
+    award_block.attr("data-original-title", authors.join(", "))
     @resetTooltip(award_block)
   resetTooltip: (award) ->
@@ -122,7 +133,7 @@ class @AwardsHandler
     nodes = []
     nodes.push(
-      "<button class='btn award-control js-emoji-btn has-tooltip active' title='me'>",
+      "<button class='btn award-control js-emoji-btn has-tooltip active' data-original-title='me'>",
       "<div class='icon emoji-icon #{emojiCssClass}' data-emoji='#{emoji}'></div>",
       "<span class='award-control-text js-counter'>1</span>",
       "</button>"

app/views/votes/_votes_block.html.haml

 .awards.votes-block
   - awards_sort(votable.notes.awards.grouped_awards).each do |emoji, notes|
-    %button.btn.award-control.js-emoji-btn.has-tooltip{class: (note_active_class(notes, current_user)), title: emoji_author_list(notes, current_user), data: {placement: "top"}}
+    %button.btn.award-control.js-emoji-btn.has-tooltip{class: (note_active_class(notes, current_user)), data: {placement: "top", original_title: emoji_author_list(notes, current_user)}}
       = emoji_icon(emoji)
       %span.award-control-text.js-counter
         = notes.count