How to make div card size equal in bootstrap class?

Question

Hi Team

I have small problem with div card, second div card size is not the same and need help. Maybe i am missing something in between, need assistance please. 

<div class="container mt-105">
    <div class="row justify-content-center">
        <div class="col-md-6">
            <div class="card border-dark rounded">
                <div class="card-body">
                    <!-- Text above Save and Close button -->
                    <div class="mb-4">
                        <p class="text-center">To create a new request and continue editing later, click "Save and Close" below.</p>
                    </div>
                    <!-- Step 1: Save and Close -->
                    <div class="mb-4">
                        <div class="row justify-content-center">
                            <div class="col-md-12">
                                <!-- Adjusted column width to 12 -->
                                <button type="button" class="btn btn-danger btn-block">Save and Close</button>
                            </div>
                        </div>
                    </div>
                </div>
            </div>
        </div>
        <div class="col-md-6">
            <div class="card border-dark rounded">
                <div class="card-body">
                    <!-- Text above Request Action button -->
                    <div class="mb-4">
                        <p class="text-center">To submit for immediate feedback, click "Request Action" below.</p>
                    </div>
                    <!-- Step 2: Request Action -->
                    <div class="mb-4">
                        <div class="row justify-content-center">
                            <div class="col-md-12">
                                <!-- Adjusted column width to 12 -->
                                <button type="button" class="btn btn-danger btn-block">Request Action</button>
                            </div>
                        </div>
                    </div>
                </div>
            </div>
        </div>
    </div>
</div>