How are user sessions counted under COUNTER Release 5 that may result in differences when comparing to COUNTER 4 usage reports?

Under COUNTER Release 5 (R5), there is a longer elapsed time for user sessions which may cause higher deduplication of download activity by the same user. So, a user could return to a previously accessed content page and have it been counted twice in COUNTER Release 4 whereas in R5 it may only be counted once. Therefore, in R5 there is a possibility of more deduplication causing slightly lower reported user activity which could be recorded as either an investigation or requests depending on the content type.