In big presentation days with lots of decks you get the inevitable situation that some slides fit in multiple presentations. Some presenters double them up, and start presenting the slide (after the apology "you have seen/heard this before" as if it was the first time).
Don't. Repetition is boredom. Your audience can/will remember. You have 2 options:
- A super short "taste" of what is about to come later. I.e., introduce what a certain company does briefly, without going into any detail or background. Do the full elaborate presentation the second time around with a quick reference to your earlier slide
- Do the full presentation early on, and give a very small recap of the story later when it comes up the second time. One solution is to present a thumbnail screen shot of the original slide plus 2 bullet points (oops, yes I said it) of the key take aways of the slide.