I think I would allow some time between the two just to monitor for any side effects. I do not know if they should be given together or not, but I never give more than one thing on a given day and usually wait at least a day or two in order to know if there are any side effects.
We are currently treating Petunia for hookworms and after giving the Advantage Multi we had almost a month of bloody diarrhea to contend with. She was absolutely loaded with hooks and eggs. We knew her stomach was having issues as a result and ended up delaying the Drontal Plus on the advice of our vet until her stools were better. This was her first dose of both, so we are hoping subsequent dosing will be less harsh on her system since so much came out of her on the first treatment. As it turned out, the Drontal Plus made her hyper. Had we followed the Prison Protocol, we wouldn't have known which med was causing either issue. I look at it like changing foods, only one change at a time so you know what is happening and what the cause is.
Good luck! These hooks are nasty.