datacloud.matchresult

Datacloud.FindDuplicatesResult[] results = Datacloud.FindDuplicates.findDuplicates(accountList);
            List<String> duplicateRecords = new List<String>();
            for (Datacloud.FindDuplicatesResult findDupeResult : results) {
                for (Datacloud.DuplicateResult dupeResult : findDupeResult.getDuplicateResults()) {
                    for (Datacloud.MatchResult matchResult : dupeResult.getMatchResults()) {
                        for (Datacloud.MatchRecord matchRecord : matchResult.getMatchRecords()) {
                            duplicateRecords.add(matchRecord.getRecord().Id);
                        }
                    }
                }
            }
            if (duplicateRecords.size() != 0) {
                account.addError('Duplicate! Records Ids: ' + string.join(duplicateRecords, ','));
            }