I beg to differ, how can the temperatures between the cylinders be different. With an air cooled engine yes, but a water cooled engine with a water pump, the temperature variations are not going so big as to affect the carb jetting.
One of my cylinders was actually running richer than the other, so i ordered a new needle to match the leaner cylinder and voila, both cylinders run the same. So the answer is yes, you can run the same needles and from memory the emulsion tubes are the same, but i will try and find my notes on this.
Just curious Andrius why you think you need new needles. Are they visibly worn or bent (how!!)?
Before messing with needles etc, have a look at a spark plug (either one) from each cylinder and check the colour. They should both be a chocolate brown colour ( refer to pics on the web if not sure). If the needles have worn this will always result in a richer mixture, causing the plugs to be black.
Note: the plug check should be done after a good blast or a normal run and stop the engine without letting it idle for too long. If either of the plugs is black, check the carbs choke mechanism is closing fully, not sticking and the plunger seat is not damaged allowing fuel to leak past. Other things to check are the float chamber needle valves (not a bad idea to change them anyway) to make sure they are not leaking but also the float height as if this is too high, also allows the fuel mixture to be richer than it should.
Hope all this helps, but it is most important to check out what IS ok before jumping to assumptions as to what is wrong.
You dont state what problems you are having and the reasons for you concluding the needles require replacing.
What model, year and mileage is your AT as it all helps in the diagnosis!
FYI, I built race engines for years, dyno testing etc and am a bit of a carb expert having had a lot of experience with re-jetting, choke sizes emulsion tubes etc. Also if you want to make your AT pull full throttle from 1500 RPM (YES!!) and be the bike it always should have been, check out my posts about altering the ignition map (somewhere on this site !)