Duke, you are wrong. You are reading the span tables the wrong way(well I hope you are basing what you say on span tables). What you are trying to say, is that if you use double bearers you can use undersize timer. But it doesnt work that way. Double bearers means a bearer EACH side of the post, not laminated together.
DIY, lamination - glued, nail, screwed, or headbutted together, is not structurally sound.