SSJS: Check Duplicate Records

<script runat="server">

    Platform.Load("core", "1");

    var api = new Script.Util.WSProxy();

    try {

        var config = {

            name: "Master Seed List",

            cols: ["Email", "ContactId"],

            filter: null,

            opts: { BatchSize: 300 },

            props: { QueryAllAccounts: false }

        };

        var result = [], moreData = true, reqID = null;

        while (moreData) {

            if (reqID) config.props.ContinueRequest = reqID;

            var req = api.retrieve(

                "DataExtensionObject[" + config.name + "]",

                config.cols, config.filter, config.opts, config.props

            );

            if (req && req.Results && req.Results.length > 0) {

                moreData = req.HasMoreRows;

                reqID = req.RequestID;

                for (var i = 0; i < req.Results.length; i++) {

                    var props = req.Results[i].Properties;

                    var record = {};

                    for (var j = 0; j < props.length; j++) {

                        var key = props[j].Name;

                        var val = props[j].Value;

                        if (key.indexOf("_") !== 0) record[key] = val;

                    }

                    result.push(record);

                }

            } else {

                moreData = false;

            }

        }

        // ✅ Debugging: Checking if data is fetched

        if (result.length === 0) {

            Write("<h3 style='color:red;'>No data retrieved from Data Extension.</h3>");

        } else {

            Write("<h3>Fetched Records:</h3>");

            Write(Stringify(result));

        }

        // ✅ Duplicate Check Logic

        var duplicateCheckAttribute = {};

        var duplicates = [];

        for (var i = 0; i < result.length; i++) {

            var email = result[i].Email;

            if (duplicateCheckAttribute[email]) {

                duplicateCheckAttribute[email]++;

            } else {

                duplicateCheckAttribute[email] = 1;

            }

        }

        // ✅ Identify duplicate emails

        for (var email in duplicateCheckAttribute) {

            if (duplicateCheckAttribute[email] > 1) {

                duplicates.push({

                    Email: email,

                    Occurrences: duplicateCheckAttribute[email]

                });

            }

        }

        // ✅ Display duplicate results

        if (duplicates.length === 0) {

            Write("<h3 style='color:green;'>No duplicate emails found.</h3>");

        } else {

            Write("<h3>Duplicate Emails Found:</h3>");

            Write(Stringify(duplicates));

        }

    } catch (error) {

        Write("<h3 style='color:red;'>Error:</h3>");

        Write(Stringify(error));

    }

</script>