Sometimes I want my son or daughter to practice a particular skill multiple times in one day. To do that, I assigned one exercise a few times. The problem with this is that Khan sees that I've assigned the same exercise multiple times and when my child completes the first assignment, Khan shows all of them as complete.
For example, today I assigned "Break apart 3-digit subtraction problems" twice so my son could get a lot of practice in. But when he finished the first assignment, Khan marked both assignments as completed just because they are the same skill.
If something is assigned twice, it should be counted individually. Parents/teachers might want a student to practice a skill multiple times (multiplication tables being a great example) but with the current system, all assignments will show as complete when the student only completed one of them.