> It has happened to me too, however I realised I had clicked / tapped on the “add to logbook button” more than once...
Same for me. Easy to do if you're on a bit of a flakey connection as the confirmation page can take a while to show up so I get nervous and hit 'add to logbook' again.
If you accidentally resend and end up with duplicates entries it is pretty easy to delete them than it once was. Just select the climbs you want to delete via the check boxes on the LHS of your logbook, then select the trash icon that appears at the top of the page.