You are able to view the list of all the auctions an individual user has registered for.
From this list you are also able to see which of your Auctioneers the auction belongs to, the Auction Status, Registration Date, Registration Status, their Spending Limit and complete several actions for that user.
Steps to Follow:
Log into the administration area
Select Users & Groups > Users from the menu bar drop down
View the user
Click on their username
Click on the Auctions tab
View the full list of auctions the user is registered to for your auctioneers. Note that auctions appear in the list even if the user is still Pending approval.
The Actions column allows you to manage the registration in the same way you would from the Registrants screen