PIN being requested twice

I managed to install my wifi certificate to my Samsung Galaxy SIII Neo. It appears to necessarily require a pin or password for the lock screen, since all other options (including pattern, which I may be OK with) are grayed out. I'll have to come to terms with that. Or so it seems. However, now the PIN is being requested twice, or rather, two (equal) PINs are being requested at startup: one for the SIM and one for the lock screen. Is there a way to turn off the lock screen PIN at startup or do I really have to remove the SIM's PIN? And in that case, can I do that? OR, can I have a one or two-digit PIN instead of a 4-digit one for the lock screen?