This is as much as I can do to get the 2 sliders (with the same number of slides) to be in sync.
var slider = $('.bxslider').bxSlider({
onSlideNext: doThis,
onSlidePrev: doThis
});
var slider1 = $('.bxslider1').bxSlider({
onSlideNext: doThis,
onSlidePrev: doThis
});
function doThis(ele, old, newi){
slider.goToSlide(newi);
slider1.goToSlide(newi);
}
What I did is assigned a function to its onSlideNext and onSlidePrev events and this function ensured both the sliders moved to the same index (this is why I emphasized on the same number slides).
Disclaimer: I do not endorse this kind of approach nor do I claim that this is a fully tested solution :) :) :)