There is a bug in Verizon Message+ which causes extra recipients and numbers to be added to a text message. This happens when you click a link in any standard Web page or app that is supposed to send a text message using an HTML href sms link.
This issue does not occur with other messaging apps like Google Hangouts, iMessage, etc.
If the SMS message you want to send has a number in the body of the message you are trying to send, then that number is added to the end of the phone number. If there is also a comma in the body of the message before the number, then the number is added as an extraneous recipient to the message which cannot be deleted.
To reproduce this issue, open the following test Web page on a phone that uses Verizon messaging: