All UpdatePanels on page updating on __doPostBack - asp.net

Question

I am experiencing off behaviour when trying to update an UpdatePanel via JavaScript when multiple UpdatePanels are on the page.
Will try to keep it short:
I'm already setting the UpdateMode to Conditional
I am passing in the correct ClientID of the UpdatePanel into the __EventTarget
In the code-behind, I am successfully able to find the target control
But for some reason, the OnLoad of every UpdatePanel on the page is fired.
Below is a snippet of code - any idea why this is happening?
Ascx:
<div class="updatePanelWrapper">
<asp:UpdatePanel ID="UpdatePanel1" UpdateMode="Conditional" RenderMode="Inline" OnLoad="UpdatePanel1Load"
runat="server">
<ContentTemplate>
<asp:Panel ID="Panel1" runat="server">
</asp:Panel>
</ContentTemplate>
</asp:UpdatePanel>
</div>
<div class="updatePanelWrapper">
<asp:UpdatePanel ID="UpdatePanel2" UpdateMode="Conditional" RenderMode="Inline" OnLoad="UpdatePanel2Load"
runat="server">
<ContentTemplate>
<div>
<asp:Panel ID="Panel2" runat="server">
</asp:Panel>
</div>
</ContentTemplate>
</asp:UpdatePanel>
</div>
CodeBehind:
protected void UpdatePanel1Load(object sender, EventArgs e)
{
UpdatePanelLoad(sender, e);
}
protected void UpdatePanel2Load(object sender, EventArgs e)
{
UpdatePanelLoad(sender, e);
}
protected void UpdatePanelLoad(object sender, EventArgs e)
{
// if only a async postback then load the control
if (ScriptManager.GetCurrent(Page).IsInAsyncPostBack)
{
// Some Logic ...
}
}
JavaScript (where I'm triggering the ASYNC PostBack):
var updatePanelWrappers = $(".updatePanelWrapper");
var availableWrapper = updatePanelWrappers[0];
var updatePanelElement = $(availableWrapper).children()[0];
var updatePanelId = $(updatePanelElement).attr("id");
window.__doPostBack(updatePanelId, "Some Arguments...");

Answer 1

With an UpdatePanel callback the page still goes through most of its lifecycle; which includes all of the Load events.