Web 2.0 mashup question

I could (possibly) work this out myself, but I’ll try you lot instead: anyone know how to combine two GPS tracks onto one map? I mean tracks as stored on Garmin’s website, and displayed like http://connect.garmin.com/activity/127111491. Specifically, I’d like to combine that track with this one. The tracks are both public, so you don’t have to assume any authentication is needed.

Update: thanks for the advice. In the end I didn’t bother with any of the fancy software and just used vim which did a perfectly good job of sticking two GPS files together.

http://connect.garmin.com:80/activity/embed/127527477

It would be nice to colour the tracks separately but I’ll live without. I’d still like to be able to do this on-the-fly, but again life is too short.

The answer is: Tidy steered a better course than me :-(.