When a verb has a companion verbed noun (anthimeria?), the forms can have different nuances. Note that verbed nouns tend to be informal (stickered, friended, SMSed etc), though some have become established (booked, experienced, etc).
For example, consider
stuck vs stickered: an apple that is stuck may be wedged somewhere or otherwise not easily removed, but an apple that is stickered is one that has a sticker pasted on it.
befriended vs friended: someone you befriend is a person you have made friends with - you might dine together, go shopping, work on projects together, and so on. On the other hand, if you say you've friended someone, you mean that you have them on your Facebook list of friends; you might not even know them personally or interact with them at all.
There may well be pairs in which the 'proper' verb is treated more literally while the verbed noun is more general, but I don't have any instances handy.
Here's my take (AuE, though AmE might differ) on the case you're asking about:
The common term is certify (see definition below). Saying that someone has been certified carries the implication that the person is competent in whatever the certificate endorses. Saying that they have merely been certificated emphasises the acquisition of the certificate but doesn't say anything about the competence that the certificate is supposed to endorse.
4 : to recognize as having met special qualifications (as of a governmental agency or professional board) within a field
'agencies that certify teachers'