SMS messages/texts are listed according to chronological order. Are the messages really close together, a few seconds, like less than a minute? Or from an iPhone user?
Try Settings > Date & time > Automatic date & time and Automatic time zone.
At this point you may want to save your Text messages with something like SMS Backup & Restore, clear all data in Text Messaging, reboot your phone, and start all over. Although the Factory Reset that you did previously should have cleared all text messages.
Settings > Apps > All > Text Messaging > Clear Data