The Take Sample keeper action does not seem to have a restriction around having more than one sample, other than it would require multiple turns.
Action: One per turn, choose a monster in an investigator's space. Place 1 sample token on the monster and then move it 1 space.
Following on from the above, if the monster does have more than one sample token on it at the start of your turn can you turn them all in at the same time for 5 threat each?
If the Monster is in an altar's space at the start of your turn, place the token on the altar and again 5 threat.
This seemed clear but a little strong for the keeper in our initial game of Mansions when playing the Fall of House Lynch 1B.