When I update a document type in a Kentico site, I see multiple entries in the Event Log for a single change. Is this normal?

The site uses workflow + versioning for these documents. The workflow has one Approval step between Edit and Publish. Kentico version is v5.5.4311 R2.

Example: I navigate to a document in the CMS Desk content tree, edit using the Form tab, change one text field and click "Save", then Approve and Publish. The Event log records these events in this order:
UPDATEDOC
CHECKOUT
UPDATEDOC
UPDATEDOC
CHECKIN
APPROVE
PUBLISHDOC

That's three "update" events for a single save.

I investigated after I noticed this same behaviour from a scheduled task I created which updates CMS Documents overnight. Its code is based on the sample code here:

http://devnet.kentico.com/docs/5_5R2/devguide/a_complete_example.htm

For each change, I use VersionManager to check out the node of the document, then I make changes and use DocumentHelper.UpdateDocument() to save them and VersionManager.CheckIn(). Then WorkflowManager moves the document to the "published" workflow step.

If this is expected behaviour, that's fine -- it just wastes some space in the Event Log. But I want to be sure this is not a problem with my Kentico installation.

This site has no custom event handler code, user-created database triggers or other processes which are activated when these documents are changed.

-- Laurence