YANBU. I've been in my job years and I only contribute to collections for people I felt really fond of and/or worked really closely with. For me, this equates to only a handful of collections in the last 7 years.
New people don't give to collections, although if the collection is for the person training you, and they've been invaluable to you, you might feel inclined.
In your case, not knowing these two people, I absolutely would not donate.
When I left my last job, I quietly explained to my boss and best "work friend" that I wanted no collection under any circumstances and if one formed naturally inside my leaving card, to please donate it to our company charity. I intend to do the same at this job ahead of my maternity leave this year.
In short: I generally dislike collections but I will get on board if I like someone enough.