Extract a list that allows specific value to have duplicates but not any other values.

Hi, I have a list that contains names of some pipe assemblies but also names of some parts that are to be shipped individually.
Does anyone know how to extract a list that would list the rows with assembly names once while listing all the rows that contain "shipped loose"?

ex:
Col A (original list) Col B (extracted list)

assembly 1
assembly 1
shipped loose
assembly 2
assembly 2
shipped loose

Col B (extracted list)

assembly 1
assembly 2
shipped loose
shipped loose

Thanks for any help!

One way

Sub test()
    Dim x
    With Range("a1", Range("a" & Rows.Count).End(xlUp))
        .Columns("b").ClearContents
        x = Filter(.Parent.Evaluate("transpose(if(" & .Address & "=""shipped loose""," & .Address & _
        ",if(countif(offset(" & .Address & ",0,0,row(1:" & .Rows.Count & "))," & .Address & ")=1," & _
        .Address & ",char(2))))"), Chr(2), 0)
        .Columns("b").Resize(UBound(x) + 1).Value = Application.Transpose(x)
    End With
End Sub

Incredible (to me, anyway), thank you very much!

You are welcome.