i think the laser engraved XXM2 on the chips is only on the Dip versions, at least on all the ones i have bought, but my smd versions just have the microchip branding and chip number.
regardless of whether its an 08m, or 40x2 smd i have only seen the engravings on the non smd parts so far, here is a pic of one of my 18M2 chips bought directly from tech supplies, it just bears the microchip info/part numbers. it does say in the info section on tech supplies that mine is an 18M2+