You can take Imodium with Pepto Bismol together and it will not harm you if you do.
However it's not advised or recommended to take Imodium with Pepto Bismol because they can interact with each other and make both the Imodium and the Pepto Bismol less effective.
Taking the Imodium with Pepto Bismol together won't make the illness go away any faster and may actually make it take longer to go away.
It's best to just take either Imodium or Pepto Bismol and not both.
But if you did take Imodium with Pepto Bismol it's not gonna harm you unless you take too much of them together.