First important thing: when you load your second jQuery.x.x.js, it will overwrite the existing $ and jQuery vars... BUT it keeps a backup copy of them (in _$ and _jQuery).
Calling noConflict(true) you restore the situation as it was before the secod js inclusion!
noConflict() gives you the running instance (the last loaded), so you can work with you version in this way
Resuming:
- first load "jquery.versionX.js"
- $ and jQuery belong to versionX
- then load "jquery.versionY.js"
- now $ and jQuery belong to versionY, plus _$ and _jQuery that belongs to versionX
- var my_jQuery = jQuery.noConflict(true);
- now $ and jQuery belong to versionX, _$ and _jQuery are probably null, and my_jQuery is versionY
you can use $("#selector").something(); for the first jquery library, and my_jQuery("#selector").something() for the second.
