I would think it would be unusual for you to be expected to send in certified copies of everything. It would be a very unreasonable thing to expect people to do such a thing if they were applying to a lot of places. If they suspect them of being fakes I'm sure they can ask for the originals if they want.

I'm always surprised that they want to see written references and put so much weight on them (see this thread for the joys of Swiss references). I mean anyone with some of their old company letterhead or skills in photoshop (or even older methods) can whip themselves up a nice reference letter in no time...