Steps to reproduce:
1. In course go to Grades and there to tab Categories and Items.
2. Click on Add Category and create a new category
3. make a new activity called Assignment and under Graded select the newly created category in the entry Grade category
-> see that this assignment is listed correctly in the Categories and Items overview
4. Duplicate assignment
-> see that the Grade category has been reset to category uncategorized for this duplicate.
-> it's not listed in the original category and has to be indívidually corrected

For this steps and results see also screenshots 1-5.png