Dear Cuong,
Please let me know the exact scenario so that i can help you in better way....
You can apply 2 Discount by using both periodic discount and manual discount on POS -:
1. Please create periodic discount which trigger automatically based on the condition.
2. Then apply either total discount % or amount based on your requirement ...
Please mark this answer as verified answer if your problem resolved ......
Thanks
Ravinder Rana
AX Retail Functional