Yes, you should definitely tell your pharmacy to change the tablets. They have messed up. There is no reason for you to have to worry about this. You should be able to concentrate on getting uric acid down to 5 or lower. You’ll also need to consider pain relief until you get uric acid safe.
All pharmacies know that allopurinol comes in 100mg and 300mg. For doses that are not divisible by 300, they should supply 100mg. If they can’t change them, then they should split them for you.