As per CAT website, if candidate has received promotion during job they can mention multiple designation separated by comma. However i am unable to insert comma, i think it dont accept special character. So should i create 2 different entries for 2 different designation??

The promotion is not count you can tell them in interview. The thing is that they only want to know if you have work experience or not so you have to write that post in which most of the time you work for company as . If you don't have a salary slip then your experience not count