OnItemrequested Problem

[Sravan]

I have a RadCombobox and for that i  have OnItemrequested,Markfirstmatch=true and i have a button if i click that button a popup will open and i will enter data and save from that popup and Entered data single item i am binding to RadCombobox.After that if i remove the element and call the OnItemrequested the same element which i bind after popup save is binding first and and renaming elements coming after that i.e 
ABC i have saved in popup it is coming like this, 
ABC
khkj..
htcdf..
gggg...
ABC
fsdfs..
gtyy..
fsdff..
ABC
htuty..