Update 2015:
This question and answer was from so many years ago when "wanting to avoid relying on Javascript" was more of a thing than it is today. Today I would not consider writing extra server-side functionality for something like this. Indeed, I think that in most instances where I would need to submit form data to more than one target, I'd probably be doing something that justified doing a lot of the logic client-side in Javascript and using XMLHttpRequest (or indeed, the Fetch API) instead.
Update 2023:
I would definitely be writing a lot of logic in the front end Javascript code and would be using the Fetch API these days.
Original answer follows:
I do this on the server-side.
That is, the form always submits to the same target, but I've got a server-side script who is responsible for redirecting to the appropriate location depending on what button was pressed.
If you have multiple buttons, such as
<form action="mypage" method="get">
<input type="submit" name="retry" value="Retry" />
<input type="submit" name="abort" value="Abort" />
</form>
Note: I used GET, but it works for POST too
Then you can easily determine which button was pressed - if the variable retry
exists and has a value then retry was pressed, and if the variable abort
exists and has a value then abort was pressed. This knowledge can then be used to redirect to the appropriate place.
This method needs no Javascript.