I was recently re-stuffing some capacitors for a radio. It’s not something I do often, but I’ve accumulated a pile of pulled vintage caps over the years so I have some on hand if a customer requests the most detailed service possible. I found a surprise inside of one!
Interesting! Someone must have purchased a radio, seen original parts and clipped them out and replaced them, without knowing that someone had re-stuffed the components already. I’ve only found this one with a new cap hiding inside, but we’ll see if any more turn up in a future project.
RETROVOLTAGE 
Interesting. But I prefere to keep the new caps as they are so down the road it would be easy for the next repairman to spot the new parts.
Yeah, me too for personal projects!
I was thinking of a compromise: Add a discrete label with the text “Restuffed”.