When you set up the candidate campaign ORCA created an individual contact for the candidate automatically.  To enter a cash contribution from the candidate you must use TRANSACTIONS>CONTRIBUTIONS>CANDIDATES PERSONAL FUNDS.  If you create a new contact entry for the candidate ORCA will treat them as an outside donor and contribution limits will apply.

You can move the cash contribution to “candidate’s personal funds”, delete the contribution from the new candidate contact you created and then delete the duplicate contact information.