Worming tablets

Is it ok to alternate between 2 different kind of worming tablets. I have been using Drontal but a few months ago the vet gave me Milbemax so i have them as well is it ok to use them then the next time Drontal?

This is what I did with Flint

As long as the dog doesn't react to either, and they both cover the same things, I don't see why not. I'd just doublecheck the frequency of dosing, e.g. if one needs to be given once a month and the other once every three months, you won't need to give the one-a-month one until the 3 months cover from the other is up.