Add the following references to HTML:
<script type="text/javascript" src="/_layouts/15/clienttemplates.js"></script>
<script type="text/javascript" src="/_layouts/15/clientforms.js"></script>
<script type="text/javascript" src="/_layouts/15/clientpeoplepicker.js"></script>
<script type="text/javascript" src="/_layouts/15/autofill.js"></script>
HTML Content:
<label for="AssignedTo">Assigned To</label>
<div id="AssignedTo"></div>
<label for="CopyTo">Copy To</label>
<div id="CopyTo"></div>
JavaScript Content:
// Call
methods on page load
$(function () {
    SP.SOD.registerSod('sp.js', '/_layouts/sp.js');
    // Call this
method to initialize the people picker
    initializePeoplePicker("AssignedTo"); // People Picker 1
    initializePeoplePicker("CopyTo");   // People
Picker 2
    // Call this
method in edit form. This method will get the data from the list using the // item
id and bind the names in page load.
    var pickerVal = BindUsersFromList();
});
// This
method will take the div ID as parameter and converts that to a people picker.
//
peoplePickerElementId: Div ID
function initializePeoplePicker(peoplePickerElementId) {
    // Create a
schema to store picker properties, and set the properties.
    var schema = {};
    schema['SearchPrincipalSource'] = 15;
    schema['ResolvePrincipalSource'] = 15;
    //
"AllowMultipleValues" property will allow multiple entries. Make it
false to restrict //this people picker to accept only one  user.
    schema['AllowMultipleValues'] = true;
    schema['MaximumEntitySuggestions'] = 50;
    schema['Width'] = 'auto';
    // Render and
initialize the picker. 
    // Pass the ID
of the DOM element that contains the picker, an array of initial
    // PickerEntity
objects to set the picker value, and a schema that defines
    // picker
properties.
    this.SPClientPeoplePicker_InitStandaloneControlWrapper(peoplePickerElementId,
null, schema);
}
Note:
The above JS code will convert the HTML div into a people picker.
Now the below JS code will get the data from the SharePoint list using item ID and bind the values to people picker.
// This
method will bind the users to people picker field in edit form.
function BindUsersFromList() {
    var dfd = new
$.Deferred();
    var divPeopleSIT = SPClientPeoplePicker.SPClientPeoplePickerDict["AssignedTo_TopSpan"];
    var divPeopleAMM =
SPClientPeoplePicker.SPClientPeoplePickerDict["CopyTo_TopSpan"];
    SP.SOD.executeFunc('sp.js', null, function () {
        JSRequest.EnsureSetup();
        var itemID = JSRequest.QueryString["ItemID"];
        if (window.location.href.indexOf('ItemID=') > -1) {
            var call = getEditformDataFromList(itemID);
            $.when(call).then(function (data) {
                if (data.d.AssignedToId != null) {
                    for (var i = 0; i < data.d.AssignedToId.results.length; i++) {
                       
divPeopleTSDM.AddUnresolvedUser({ 'Key': GetUserLoginName(data.d.AssignedToId.results[i]) }, true);
                    }
                }
                if (data.d.CopyToId != null) {
                    for (var i = 0; i < data.d.CopyToId.results.length; i++) {
                       
divPeopleSIT.AddUnresolvedUser({ 'Key': GetUserLoginName(data.d.CopyToId.results[i]) }, true);
                    }
                }
            });
            dfd.resolve();
        }
    });
    return dfd.promise();
}
// This
rest call will take the item ID as input and give that Item data in return.
//
itemID: List Item ID
function getEditformDataFromList(itemID) {
    return $.ajax
    ({
        url: _spPageContextInfo.webAbsoluteUrl
+ "/_api/web/lists/GetByTitle('LIST NAME
HERE')/items(" + itemID + ")",
        method: "GET",
        headers: { "Accept": "application/json; odata=verbose" },
    });
}
// This
will take the People picker Id and return the entered user's Login Name
function GetUserLoginName(pickerID) {
    var userName;
    $.ajax({
        url: _spPageContextInfo.webAbsoluteUrl
+ "/_api/Web/GetUserById(" + pickerID + ")",
        type: "GET",
        async: false,
        headers: {
            "X-RequestDigest": $("#__REQUESTDIGEST").val(),
            "content-type": "application/json;odata=verbose",
            "accept": "application/json;odata=verbose"
        },
        success: function (userData) {
            userName = userData.d.LoginName;
        }
    });
    return userName;
}
Now, get the number of users entered in the people picker field.
var getUsersData = getUserIdsFromPicker(valObj.Id);
var length = getUsersData.length;
// Get
the user ids of the persons entered in the people picker
// divID:
ID of the div/PeoplePicker 
function getUserIdsFromPicker(divID) {
    var pickerDiv = "#" + divID + "";
    noOfUser = $(pickerDiv + "_TopSpan_ResolvedList").children().length;
    userIds = new Array(noOfUser);
    $(pickerDiv + "_TopSpan_ResolvedList").children().each(function (index, value) {
        $.when(GetUserId($(this).attr("sid"))).then(function (data) {
            userIds[index] = data.d.Id;
        });
    });
    return userIds;
}
// This
will return a object which will have the user Ids of the person. 
//
userName: SID of the user
function GetUserId(userName) {
    var siteUrl = _spPageContextInfo.siteAbsoluteUrl;
    return $.ajax({
        url: siteUrl + "/_api/web/siteusers(@v)?@v='" +
            encodeURIComponent(userName) + "'",
        method: "GET",
        async: false,
        headers: { "Accept": "application/json;
odata=verbose" },
    });
}
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