Test nhé 
Sub GhepChuoi()
lr = Range("A" & Rows.Count).End(xlUp).Row
i = 2
Do While i <= lr
If Range("A" & i).Value <> Range("A" & i - 1).Value Then
chuoi = Range("B" & i).Value
j = 1
If Range("A" & i).Value = Range("A" & i + 1) Then
chuoi = chuoi & ";" & Range("B" & i + 1).Value
j = 2
If Range("A" & i).Value = Range("A" & i + 2) Then
chuoi = chuoi & ";" & Range("B" & i + 2).Value
j = 3
End If
End If
Range("C" & i).Value = chuoi
End If
i = i + j
Loop
End Sub
