When a constituent registers on a web form and it creates a duplicate record, the Registrants tab on an event record shows their name as the registrant. Once the duplicate record has been merged with the original constituent record, the registrant name on the event changes to "(unnamed guest)".
We are currently evaluating this issue and will update this article when we have more information.
Steps to Duplicate
On an event registration web form, complete an order without logging in
Search for the constituent name in Altru to see that it created a duplicate record
Go to Events, search for and open the event record
Select the Registrants tab
See that the constituent's name shows as the registrant
Go to Constituents > Duplicates > Merge Two Constituents
Choose the duplicate record as the Source Constituent, and the original record as the Target Constituent and complete the merge
Go back to the event record and select the Registrants tab
See that the registrant name now shows "(unnamed guest)" and the constituent's name shows as the host