Falsification of Documents

I have a friend who was accused of duplicating audits in a call center since it was seen on a masterfile that 2 people had the same audits within the same week. He has presented proofs, hard copies of the signed documents, to prove that the audits were not intentionally duplicated but was due to an error in uploading them to the masterfile. His supervisor then talked to him and told him that he may be free from the case of duplicating audits but will then be charged for negligence and carelessness. The supervisor also stated that they have additonal proofs that audits were duplicated in the previous months.
1. Can the supervisor issue another memo using the same evidence but a different offense? In this case, from falsification / duplication of audits to negligence?
2. If there will be an administrative hearing, can the supervisor bring other documents that may be used as his evidence to prove that the employee has duplicated audits aside from the ones that were stated in the memo initially given to the employee?

the answer is yes, there can be a new investigation and new evidence can be brought forth.

the issue here is whether the negligence was both gross AND habitual.