[jQuery] is this legal according to the jQuery license

Hello, I need to use jQuery lib in a script that will be included in
my clients sites.
My script will be included last in the body of a html page, and
jQuery lib will be included dynamically from my script.
Can anyone tell me is this going to have conflict with older jQuery
libraries and with other libraries. If it's going to have conflict can
someone tell me hot to solve it.
I have made some modification on jquery, can someone tell me if this
is legal according to the jQuery license.

Here is the changes they are on the beginning of the script:

(function(){

var
// Will speed up references to window, and allows munging its
name.
window = this,
// Will speed up references to undefined, and allows munging its
name.
undefined,
// Map over jQuery in case of overwrite
_jQuery = window.AR_jQuery,
// Map over the $ in case of overwrite
_$ = window.AR_jQuery,

jQuery = window.AR_jQuery = function( selector, context ) {
// The jQuery object is actually just the init constructor
'enhanced'
return new jQuery.fn.init( selector, context );
},

I'll wait for response.

Thanks