If a student texts into our system, and we don't have a student already associated to their phone number, we create a guest account for them so we have something to associate that message with. It's possible that your student texted in a few days before the person existed in our integration with a name and that number, so it will look like there is a "shadow" account. If you create a zendesk ticket, we can delete the extra guest student so you'll only get one notification per message.
The other way it's possible to have a guest account with the same phone number as a student is through the mobile app. If a student downloads the mobile app, when they click continue as guest we will create a guest account for them. If they open up preferences and add their phone number, we will associate that to their guest account. If they then come over from the integration with their new phone number, we won't combine the records together, since we merge on first name, last name, email, and phone number. The guest will have the first name of "Guest" and last name of a unique identifier in our system.
If the student already exists in our system, the previous scenario can still happen if the student signs out of their guest account and creates a new account using the demographic information we have for them. This will still maintain their guest record. They should create an account while still logged in as that guest account so the two records merge.