Same course counted twice on space

Steps to reproduce the issue:

1. Switch to organization

2. Purchase a given cycle of a course

3. Check numberOf.course of Shopping Space

4. Purchase a different cycle of the same course

5. Check numberOf.course of Shopping Space

Expected result: count at step 3 and 5 are the same

Actual result: count at step 5 increased

Note: here we are not taking into account if the shopping space already contains the course