Approval workflow not ended after the last participant approved the document

I started an approval workflow on a document, with 2 participants.
1. Participant N° 1 approves the document.
2. Participant N° 2 approves the document.
-> The document becomes Approved. But when I click on Workflow tab, the approval workflow is not ended and workflow form is displayed like if participant 2 still had to approve the document.