Verification of genuine Botox quantity

Are you checking?
 If you fit a whole bottle of 50 units into a square jaw, it will literally be easy to check the genuine quantity.
 However, in the case of Xeomin, 50 units are not available, so you will have to share a 100-unit bottle.
 In this case, how do you check the genuine quantity?
 When you open a new product, you can at least confirm that only half is used through the dilution process, but
 if it's the second time, you don't know how much saline solution is in it, right?
 How do you check for those who have been treated with Xeomin or those who have had wrinkles between their eyebrows... or had difficulty checking each bottle neatly because they received a small amount
 ?