Slides names must be unique so you must be trying to name other slides with an existing name. You need to explain why.
If you just need to split out 1,5 and 17 you don't need to name at all/
Sub chex()
Dim osource As Presentation
Dim otarget As Presentation
Set osource = ActivePresentation
Set otarget = Presentations.Add
osource.Slides.Range(Array(1, 5, 17)).Copy
Set otarget = Presentations.Add
otarget.Slides.Paste (otarget.Slides.Count + 1)
End Sub
If it's something else you need to explain clearly exactly what you are trying to do.