Trouble getting to PayPal Buy Now Buttons to work on a single page in ASP.NET

I confess I am a noob to asp.net and web forms. I’m having an issue incorporating a few PayPal Buy Now buttons on a single page. Basically, the problem is no matter which “Buy Now” button is clicked, the user is taken to paypal to buy the product represented by the last button on the page.

The code for my first button is something like this…

<input type="hidden" name="cmd" value="_s-xclick">
<input type="hidden" name="hosted_button_id" value="ABC123">
<asp:ImageButton runat="server" id="PPImageButton1" PostBackUrl="https://www.paypal.com/cgi-bin/webscr" ImageUrl="https://www.paypal.com/en_US/i/btn/btn_buynow_SM.gif"/>

My second button is similar to…

<input type="hidden" name="cmd" value="_s-xclick">
<input type="hidden" name="hosted_button_id" value="ABC456">
<asp:ImageButton runat="server" id="PPImageButton2" PostBackUrl="https://www.paypal.com/cgi-bin/webscr" ImageUrl="https://www.paypal.com/en_US/i/btn/btn_buynow_SM.gif"/>

How can I make the first button send value ABC123 to the PayPal service instead of ABC456?

Thanks in advance.

Trouble getting to PayPal Buy Now Buttons to work on a single page in ASP.NET