However, if you lose the pass certificate, it can't be replaced, so you'll have to take it again. So, just make sure you keep it safe for both your ILR and UK citizenship applications (if you will be applying for citizenship).
I'm pretty sure you don't have to take the test again if you loose the pass certificate.
They can't be replaced because they are stamped and signed by the official at the test center, but each certificate has a unique identifying number and as I understand it the pass result is electronically forwarded to UKVI.
I think that's also the reason why you can't book an in-person appointment for ILR within 2 days of passing your life in the UK test, so that the result has time to come through to them.
I did a bit of searching online too and found some anecdotal evidence that if you have lost the certificate, it's not a problem, you don't have to re-sit the test.
It's easier if you have a note of the certificate number but from what I read, even without that, they'll be able to dig up your result.
But yeah, best not to loose it in the first place and definitely scan it/copy it/make a note of the number somewhere else, just in case you do!