asp.net core How do I implement GroupBy twice?

Question

The results of my query are displayed in a selection of div as below

 

 

 

 By applying a GroupBy, view below, I managed to hide duplicates in Step No, see in the picture below as well. The questions is, how do I do the same for Activity?

  

@foreach (var group1 in Model.JSAViewList.GroupBy(s => s.StepNo))
    {
        <div class="row no-gutters">
            <div class="col-md-1">
                <label class="form-control text-white" style="background-color:mediumorchid">Step No:</label>
            </div>
            <div class="col-md-11">
                <div class="row no-gutters">
                    <div class="col-md-3">
                        <label class="form-control text-white" style="background-color:mediumorchid">Activity:</label>
                    </div>
                    <div class="col-md-2">
                        <label class="form-control text-white" style="background-color:mediumorchid">Hazards:</label>
                    </div>
                    <div class="col-md-2">
                        <label class="form-control text-white" style="background-color:mediumorchid">Controls:</label>
                    </div>
                    <div class="col-md-2">
                        <label class="form-control text-white" style="background-color:mediumorchid">PPEs:</label>
                    </div>
                    <div class="col-md-2">
                        <label class="form-control text-white" style="background-color:mediumorchid">Responsible:</label>
                    </div>
                </div>
            </div>
        </div>

        <div class="row no-gutters">
            <div class="col-md-1">
                <span class="form-control">@Html.DisplayFor(model => group1.Key)</span>
            </div>
            <div class="col-md-11">
                @foreach (var item in group1.OrderBy(s => s.StepNo).ThenBy(s => s.Hazard))
                {
                    <div class="row no-gutters">
                        <div class="col-md-3">
                            <span class="form-control">@Html.DisplayFor(modelItem => item.ActivitySec)</span>
                        </div>
                        <div class="col-md-2">
                            <span class="form-control">@Html.DisplayFor(modelItem => item.Hazard)</span>
                        </div>
                        <div class="col-md-2">
                            <span class="form-control">@Html.DisplayFor(modelItem => item.Controls)</span>
                        </div>
                        <div class="col-md-2">
                            <span class="form-control">@Html.DisplayFor(modelItem => item.PPE)</span>
                        </div>
                        <div class="col-md-2">
                            <span class="form-control">@Html.DisplayFor(modelItem => item.Responsible)</span>
                        </div>
                    </div>
                }
            </div>
        </div>
    }