Incorrect information in participant record for additional participants

On registering multiple participants to an event configured with a price set, the second and additional participants have incorrect data in the civicrm_participants table.

The fee_amount field is NULL, even though the fee_label and corresponding civicrm_line_item records are correct. This field is needed in multiple places in the CRM, including the event revenue reports that are calculated based on summing this column. So this is a major issue.

This has been reproduced on the 4.3.3 demo - see event Conference Test (ID: 14). Find participants for this event and you will see that the column 'Amount' is blank for the second participant, which was registered as an additional participant to the first.