If you have two contact records that you know are the same person you can merge them together and preserve any bookings and details associated with both.
The example below shows a contact entered incorrectly.
Daniel James will need to be merged into Dan James since that is the main contact already in the contact list.
To do this open the incorrect contact record and click edit. On the next page in the sidebar click the option "Merge into another contact".
Next select the contact to merge by checking the box next to their name, then click merge at the top of the page. Once completed you will receive an email to confirm the merge is complete.