Steps to reproduce

1. Enable Line Items under Administer --> Administration Console --> Donation Receipts Profiles --> General Settings
2. Setup a profile for the financial type donation
3. Create a price set for event, with one field of financial type event fee and with a checkbox field with multiple options all of type donation
4. Register a contact for this event and select at least two checkboxes (so that there are two or more line items for donations)
5. Now try to generate a donation receipt

Expected behaviour

A donation receipt is created

Actual behaviour

An error is thrown, DB Error: already exists

Work around

Alter your database with the query below:

ALTER TABLE `donrec_snapshot` 
  DROP PRIMARY KEY, 
  ADD PRIMARY KEY (`id`), 
  ADD UNIQUE `snapshot_contrib_line_item` (`snapshot_id`, `contribution_id`, `line_item_id`);

Comment

This is a follow up of #136