No, because let’s say for example that something cost $100.00 so you take 20% (or $20) off of the 100 and you’re left with $80.00. Well then you have your 10% off coupon so you take 10% off of 80, which is 8 dollars. So now you’re at $72.00.
But if we just took off 30% from 100 originally, you would be at $70.00
So no it wouldn’t be the same. If you wanted to check the idea yourself just use different numbers and see if they match at the end.