I just asked a [question](http://serverfault.com/questions/417186/who-is-carrierzone-and-what-do-they-do-with-email-through-a-custom-domain) involving DNS MX records and noticed that there are two separate tags that appear to both concern MX records: [tag:mx] and [tag:mx-record].  
Do these need to be merged?  
Are there other tags in similar situations?