Hi nedash,

The same way you have to add another hiddenfield and set the value on selection. Then code behind access the hiddenfield values to pass as paramater.

I have assigned two click event for the two Repeater. When dropdown-menu item selected respective click event is executed and hiddenfields are set with selected item.

Check the below example.

HTML

<link rel="stylesheet" type="text/css" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" />
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js"></script>
<script type="text/javascript" src="https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js"></script>
<script type="text/javascript">
    $(function () {
        $(".dropdown-menu li a[id*=Repeater2]").click(function () {
            $(this).closest('.dropdown').find(".btn:first-child").text($(this).text().trim());
            $(this).closest('.dropdown').find(".btn:first-child").val($(this).text().trim());
            $("[id*=hfSelectedTransfer]").val($(this).text().trim());
        });

        $(".dropdown-menu li a[id*=Repeater3]").click(function () {
            $(this).closest('.dropdown').find(".btn:first-child").text($(this).text().trim());
            $(this).closest('.dropdown').find(".btn:first-child").val($(this).text().trim());
            $("[id*=hfSelectedMetraj]").val($(this).text().trim());
        });
    });
</script>
<br />
<center>
    <div class="row">
        <div class="col-md-6">
            <div class="Tmelk1">
                <asp:HiddenField runat="server" ID="hfSelectedTransfer" />
                <div class="dropdown">
                    <button class="btn btn-secondary dropdown-toggle" type="button" id="dropdownMenuButton"
                        data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
                        Select Transfer
                    </button>
                    <div class="dropdown-menu" aria-labelledby="dropdownMenuButton">
                        <asp:Repeater ID="Repeater2" runat="server">
                            <ItemTemplate>
                                <li><a target="_blank" class="dropdown-item" id="A1" runat="server">
                                    <%# Eval("Transfer") %></a></li>
                            </ItemTemplate>
                        </asp:Repeater>
                    </div>
                </div>
            </div>
        </div>
    </div>
    <div class="row">
        <div class="col-md-6">
            <div class="Tmelk">
                <asp:HiddenField runat="server" ID="hfSelectedMetraj" />
                <div class="dropdown">
                    <button class="btn btn-secondary dropdown-toggle" type="button" id="Button1" data-toggle="dropdown"
                        aria-haspopup="true" aria-expanded="false">
                        Select Metraj
                    </button>
                    <div class="dropdown-menu" aria-labelledby="dropdownMenuButton">
                        <asp:Repeater ID="Repeater3" runat="server">
                            <ItemTemplate>
                                <li><a target="_blank" class="dropdown-item" id="A2" runat="server">
                                    <%# Eval("metraj") %></a></li>
                            </ItemTemplate>
                        </asp:Repeater>
                    </div>
                </div>
            </div>
        </div>
    </div>
    <div class="row">
        <div class="col-md-6">
            <asp:ImageButton runat="server" OnClick="ImageButton1_Click" AlternateText="Get Estat Info" />
        </div>
    </div>
</center>

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        System.Data.DataTable dt = new System.Data.DataTable();
        dt.Columns.Add("Transfer");
        dt.Columns.Add("metraj");
        dt.Rows.Add("Transfer 1", "metraj 1");
        dt.Rows.Add("Transfer 2", "metraj 2");
        dt.Rows.Add("Transfer 3", "metraj 3");
        dt.Rows.Add("Transfer 4", "metraj 4");
        Repeater2.DataSource = dt;
        Repeater2.DataBind();
        Repeater3.DataSource = dt;
        Repeater3.DataBind();
    }
}

protected void ImageButton1_Click(object sender, ImageClickEventArgs e)
{
    string selectedTransfer = hfSelectedTransfer.Value;
    string selectedMetraj = hfSelectedMetraj.Value;
}

VB.Net

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
    If Not Me.IsPostBack Then
        Dim dt As System.Data.DataTable = New System.Data.DataTable()
        dt.Columns.Add("Transfer")
        dt.Columns.Add("metraj")
        dt.Rows.Add("Transfer 1", "metraj 1")
        dt.Rows.Add("Transfer 2", "metraj 2")
        dt.Rows.Add("Transfer 3", "metraj 3")
        dt.Rows.Add("Transfer 4", "metraj 4")
        Repeater2.DataSource = dt
        Repeater2.DataBind()
        Repeater3.DataSource = dt
        Repeater3.DataBind()
    End If
End Sub

Protected Sub ImageButton1_Click(ByVal sender As Object, ByVal e As ImageClickEventArgs)
    Dim selectedTransfer As String = hfSelectedTransfer.Value
    Dim selectedMetraj As String = hfSelectedMetraj.Value
End Sub

Screenshot