I've seen it come up as both, a reset will do and should go away.
A quick tidbit for those Visual Voicemails that aren't working functioning properly. You may still have the "Enhanced Voicemail" feature on your account. You'll need to have this removed by calling in or going to a store and getting the Visual Voicemail soc added to your account.
If you switch to google voice instead of t-mo's visual voicemail you will only get one voicemail. Plus it can shoot you an sms, or an email too. It makes it easier overall for me to manage my voicemails on my PC if i'm in front of it since it transcribes the messages.