It is crucial to avoid using the same IDs for fields in your code. Each ID should be unique for different fields.

According to XHTML 1.0 Spec,

In XML, fragment identifiers are of type ID, and there can only be a single attribute of type ID per element. Therefore, in XHTML 1.0 the id attribute is defined to be of type ID. XHTML 1.0 documents MUST use the id attribute to define fragment identifiers on specific elements to ensure well-structured XML documents. Refer to the HTML Compatibility Guidelines for backward compatibility with XHTML documents served as text/html.

I have revised your code for better functionality. Here is a demo link to see the changes in action:

https://jsfiddle.net/4onh3nrx/1/

HTML

<div class="container">
    <div class="row clearfix">
        <div class="col-md-12 column">
            <table class="table table-bordered table-hover" id="tab_logic">
                <thead>
                    <tr >
                        <th>

                        </th>
                        <th class="text-center">
                            #
                        </th>
                        <th class="text-center">
                            Name
                        </th>
                        <th class="text-center">
                            Address
                        </th>
                        <th class="text-center">
                            Mobile
                        </th>
                        <th class="text-center">
                            Action
                        </th>
                    </tr>
                </thead>
                <tbody>
                    <tr id='addr0'>
                        <td>
                            <input type="checkbox" class="check_0">
                        </td>
                        <td>
                            <input type="text" name='name0'  placeholder='Name' class="form-control name" id="name" required>
                        </td>
                        <td>
                            <select id="country" name="country" class="form-control country"> 
                                <option value="">select an option</option>
                                <option value="Afghanistan">Afghanistan</option>
                                <option value="Albania">Albania</option>
                            </select>
                        </td>
                        <td>
                            <input type="text" name='mail0' class="form-control mail_id" id="mail_id" required>
                        </td>
                        <td>
                            <input type="text" name='mobile0' placeholder='Mobile' class="form-control mobile" id="mobile" required>
                        </td>
                        <td>
                            <a href="#" class="btn btn-warning add-row">
                                <i class="glyphicon glyphicon-plus"></i>
                            </a>
                        </td>
                    </tr>
                </tbody>
            </table>
        </div>
    </div>
    <a id="add_row" class="btn btn-default pull-left">Add Row</a><a id='delete_row' class="pull-right btn btn-default">Delete Row</a>
</div>

JS

<script>
    $(document).ready(function () {
        $("#mobile").keypress(function (e) {
            if (e.which != 8 && e.which != 0 && (e.which < 48 || e.which > 57)) {
                return false;
            }
        });
    });

    $(document).on('click', '.delete-row', function(){
        $(this).closest('tr').remove();
    });

    $(document).on('click', '.add-row', function(){
        var tr = $(this).closest('tr');
        var field = [
            '.name', '.country', '.mail_id', '.mobile'
        ];
        console.log(tr);
        var flag = false;
        for(var i = 0; i < field.length; i++) {
            var ele = $.trim($(tr).find(field[i]).val());
            console.log(ele);
            console.log($(tr).find(field[i]));
            if(!ele.length) {
                flag = true;
                $(tr).find(field[i]).addClass('error');
            } else {
                $(tr).find(field[i]).removeClass('error');
            }
        }

        if (!flag) {
            var html = "<tr><td><input name='checkbo" + i + "' type='checkbox' placeholder='' class='check'  /></td><td><input name='name" + i + "' type='text' placeholder='Name' class='form-control name input-md'/> </td><td><select name='country" + i + "' class='form-control country'><option value=''>select an option</option><option value='afghan'>Afghanistan</option><option value='albania'>Albania</option></select></td><td><input  name='mail" + i + "' type='text' placeholder='Mail'  class='mail_id form-control input-md'></td><td><input  name='mobile" + i + "' type='text' placeholder='Mobile'  class='form-control input-md mobile'></td><td><a href='#' class='btn btn-warning add-row'><i class='glyphicon glyphicon-plus'></i></a><a href='#' class='btn btn-danger delete-row'><i class='glyphicon glyphicon-minus'></i></a></td></tr>";
            $(html).insertAfter(tr);
        }
    });
</script>