make sure on the temp value you have it set to Key assigns only
I'm not sure that you can't import twice (it seems like I have done that before)
but if that is the issue, then you can still use 2 lines on the import, just make sure only one of the two conditions succeed so that your not importing twice
first sales order number action
Calculate ""P""+Temp002$ -
Set this condition to If Temp003$=""ipad""
second sales order number action
Calculate ""W""+Temp002$
Set this condition to ""if Temp003$<>""Ipad