When a loan is triggered on Ebook Central for a title owned under the NL access model or a DDA title, there will be two entries in the usage report. All pre-trigger usage will be recorded as a ‘free view’ use type, and then any usage occurring after the loan is triggered is recorded on a separate line.
For example, for an NL book with a loan triggered by ‘view time’:

detail from usage report showing usage before and after 'view time' trigger

The first entry (bottom line) is for the read online time prior to the loan trigger. The second entry is for usage under that triggered loan. Here, you can see the book was open in the online reader for 10 minutes of ‘free view’ time, and then after the loan was triggered it was read for an additional 27 seconds. (for an explanation of how there can be 10 minutes of ‘free view’ time for an NL title, see Ebook Central Admin: Trigger events for NL loans, DDA-discoverable books, and Extended Access coverage)

Similarly, if an STL is triggered for a DDA title, there is usage logged before the trigger event and after the loan is triggered:

Usage report detail of before- and after-trigger usage for STL

Other trigger events (copy, print, chapter download, full-document download) will also result in a separate entry for post-trigger usage:

Usage report detail showing before- and after- trigger usage for downloaded title

In the above example, the book was read online for a short time and then full-document downloaded. The second usage entry is for usage after the title was triggered for autopurchase due to the download.

Usage report detail showing before- and after-trigger usage for STL triggered via copy text action

In this example, a title was read online for a short time and then an STL was triggered due to using the ‘copy’ function. After the loan was triggered, there is some additional read online time.

Because the pre- and post-trigger usage is logged on separate lines, if you run a report for only trigger events, you will not see the read online time that led up to a ‘view time’ trigger – only the read online time after the trigger. This is why you’ll often see ‘view time’ trigger events with read online times below the 5 minute free view allotment.