problems with vb list

i have this problem with vb lists in grasshopper:

-i introduce SPRINGS as input List(Of On3dPoint),
-i declare REJILLA as input List(Of On3dPoint),
-then i equal REJILLA to SPRINGS
-i operate with REJILLA
-and when i look at the output values for SPRINGS and REJILLA, both
are modified by the operator!
so my question is:
how can i introduce a list in vb and keep it non-modified (while i
operate with another one created in vb that has inherited its values)

the script:

thanks a lot!
jorge

Sub RunScript(ByVal puntos As List(Of On3dPoint), ByVal springs As List
(Of On3dPoint), ByVal k As Double, ByVal m As Double, ByVal iter As
Integer, ByVal num_f As Integer, ByVal num_c As Integer)
Dim i As Int16
Dim p0 As New On3dPoint()
Dim cont As Int16
Dim num_i As Integer
num_i = num_f + 2
Dim num_j As Integer
num_j = num_c + 2
Dim max_i As Integer
max_i = num_f - 1
Dim max_j As Integer
max_j = num_c - 1
Dim j As Integer
Dim p_max As Integer
Dim p_list As New List(Of On3dPoint)
p_max = springs.Count() - (num_f + num_c)
Dim rejilla As New List(Of On3dPoint)
For i = num_j To p_max Step num_j - 1
For j = i To i + num_c - 2
rejilla.add(springs(j))
Next
Next
While cont < iter
For i = 0 To rejilla.count() - 1
rejilla(i).x += 3
rejilla(i).y += 4
rejilla(i).z += 6
print("posicion " & rejilla(i).x & " " & rejilla(i).y & " " &
rejilla(i).z)
Next
cont += 1
End While

SP = springs
RJ = rejilla
PT = puntos