I'm lucky enough to have a few very nice pieces of occasion wear.
Whilst they are still in fashion I have no hesitation whatsoever in wearing them to events even when the same people are present. They are "investment" pieces, chosen precisely because they can be worn again.
I'll admit I find the idea of disposable fashion pretty abhorrent tbh (environmentally wasteful and encouraging poor working conditions).
That said, I generally can't remember who wore what to every function and I don't suppose I'm any more memorable than anyone else (the stand outs for me are always people who look like didn't bother).
Also, I think people underestimate the power of accessories. The same dress, but with different shoes, bag, hat, jewellery, hair styled differently, a shawl/shrug/jacket/silk scarf etc etc make a very different look (I'm not suggesting you necessarily change/wear all of the above btw!!).
If it's an outfit you like, of course wear it again 