textindex change firing multiple time with 2 gridview in asp.net c#

I have two gridview in one update panel one gridview1 working with selected index change and another gridview2 for entry details based gridview1 selection. gridview2 having dropdown and textbox it works both on mouse pointer and tab saving to db through textindexchanged event if end user press tab it works fine else if after typing in textbox they directly cilck to griview then textindex change firing twice in asp.net c# web application