couple of helpers for you
to get both the remotes working do the following
1: key in ignition and turn till instrument lights come on
2: remove key and hold down 1 of the buttons
3: press the other 3 times
4: this should lock/unlock the vehicle whilst also flashing the lights
to get the 2nd remote working do steps 2 & 3 as soon as the 1st remote is programmed (this is what i have done with mine and i now have a 2 remote keys working fine)
the transponder needs to be the same type as used in your vehicle, the type should be stamped on the key blade (for example W or W3)
as far as i know transponders can be used as many times as you like as i've carried out loads of trial and error attempts and never had a
problem re-using them
to programme the actual key you need the 4 digit immobiliser code
if you don't have this your local dealer can get it for you (but they will need the 14 digit code from the immobiliser which needs to be read from the vehicle using vag com or similar)
once you have the 4 digit code it's just a matter of
coding it all in using vag com or similar
hope that helps a bit
(if anyone else is after remotes i have two more on ebay at the mo
)