IMPORTANT: Testing this requires git-abilities in order to switch of branch and/or apply patches. IMPORTANT: This needs to be tested on all 2.x branches and master, so all the steps below are for each branch: 1) BEFORE applying the patch, create one course, with course completion enabled. 2) Add 1-2 students to it. 3) create one activity (any is ok), for example one "page" and define activity completion to require viewing the resource. 4) define course completion to include the page resource just created. 5) logged as student, view the page. 6) TEST: As admin, look to the course-completion report and verify that the student appears to have completed the page resource. 7) Backup the course, with users and all activities. 8) duplicate the activity (x2 icon). Should end ok. (Note, in 20_STABLE where the duplication feature was not available you can go to the page resource and then perform one backup & restore of that activity. It's 100% equivalent). 9) TEST: go to the completion report. Error happens. 10) TEST: Go to the DB, look the course_completion_aggr_methd table, some records for the course are duplicated. 11) SWITCH to branch having the patch applied OR apply it for the current branch. 12) Go to site main page. Upgrade process should be ignited. 13) TEST: The upgrade process ends without error. 14) TEST: Go to the DB, look the course_completion_aggr_methd table, the duplicate records in 10) are out. 15) TEST: go to the completion report. No error happens. 16) Duplicate the page resource again. 17) TEST: go to the completion report. No error happens. 18) TEST: The completion report continues showing only one page resource. 19) Restore the course backup created in 7) restoring onto current course and adding information. 20) TEST: The restore ends without problem 21) TEST: go to the completion report. No error happens. 22) TEST: In the completion report now there are 2 page resources shown, both with the student in 5) being shown as completed.