VBA add text only if not there

[dukeofscouts]

Ok I've got a worksheet change code that runs to add the text "~~SPECIAL~~" to the target's value.

The issue is that as the working code runs the next time that cell is edited, the text reads:
~~SPECIAL~~
~~SPECIAL~~
target.value

I've tried to use Target.Replace to fix this, but to no avail. any suggestion?

Current code:
Target.value = "~~SPECIAL~~" & Chr(10) & Target.value
Code result:
~~SPECIAL~~
~~SPECIAL~~
Target.value

Attempted Code:
Target.replace ("~~SPECIAL~~", "")
Target.value = "~~SPECIAL~~" & Chr(10) & Target.value
Code result:
~~SPECIAL~~
~~
Target.value

Desired Code:
???
Code result:
~~Special~~
Target.value

 

[hsk]

May be

If Left(Target.Value, 11) <> "~~SPECIAL~~" Then
    Target.Value = "~~SPECIAL~~" & Chr(10) & Target.Value
End If

 

[dukeofscouts]

User.thankful = VeryTrue