how to merge array if field is same

how to merge array if field is same

Array
(
[Id] => 896
[item] => Combo Cheesesteak - Mushrooms & Peppers
)
Array
(
[Id] => 890
[item] => Burrito | Steak
)
Array
(
[Id] => 889
[item] => Burrito | Chicken
)
Array
(
[Id] => 888
[item] => Burrito | Chicken
)
Array
(
[Id] => 888
[item] => Burrito | Carnitas
)
Array
(
[Id] => 888
[item] => Nantucket Nectar | Apple
)
Array
(
[Id] => 887
[item] => Tempura
)
Array
(
[Id] => 887
[item] => Chicken Karaage
)
I want to merge the item if id is same if it is not simple echo in php???