Cat Cerenia Overdose - Urgent

My cat with diabetes and triaditis was prescribed 4mg - 8mg of cerenia (maropitant citrate) daily until we get her seen by an internist. I just learned that two hours ago, my mom gave her 16mg accidentally. I am fuming. Her regular vet said she should be fine, and the ER said they’d get back to me, but I’ve gotten bad advice from vets before so wanted additional opinions. She weighs ~11.5lbs. Would this be deadly/do I need to take her in? TIA.