technical help please

hey guys i am getting my second ecu hopefully this thursday and so what i am going to do is take it to a shop and get it i guess programed so i can make it work with my car. but after i have him program the ecu for my car i am taking it out and getting it sent away to be chipped so they help i need is that when it gets sent back to me will i have to have it programmed with a vagcom again or will i be able to just switch them when i get it back cause i am doing the codes with the vagcom now. what will i have to do cause i am going to use the vagcom to code it friday to make sure it works with my car than i am sending it off so do i need to have to use the vagcom every time i switch ecu's thanks guys. i have two so how does it work with switching it back and forth???? and do u need a vagcom everytime?
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