Label: how to cite the fictional notices.
N3 and N4 both say the spare cable is in drawer 2. Two notices in this packet support that sentence.
N1 says 09:00. N2 says 09:30. Those two sentences disagree.
One notice states a claim. Two agreeing notices are additional support, but this packet does not establish their independent acquisition or truth. Copies of one claim would not be independent verification.
No real bulletin board was visited.