A bug Windows Phone 8 was discovered, for its text messaging feature. Thankfully, there is workaround available as well.
When you compose to send a voice message, and edit it before sending it, the phone automatically adds a second name(quite literally) to the list. The message sending eventually fails and gives an error. Turns out, the second name added to the list is actually the Second name/Surname/Last name of the original recipient.
It happens only when the People Hub is set to Display names by Last,First order, if you reverse(First,Last) it, it solves the issue. But if this doesn’t solve it for you, you will have to wait for Microsoft to roll out an update. If you wish to check in more details regarding this bug, read Todd 4 Tech.
Source: Todd 4 Tech