When people make overhead beams out of three 2 by 4's......I've always been curious why on some of the build projects it looks like (from pictures looking up at them) that the center 2x sandwitched between the outer two appears to be a size smaller. Is this done for appearance sake because if it is done, in my opinion it does or would look better. Maybe this is just my imagination, but have always been curious.
For headers, beams above windows and doors, it is common to use two 2x's with a sandwich filling of OSB or plywood to make the width/thickness come out to 3-1/2 or 5-1/2 to match the framing. Other overhead beams could also be sandwiched to match other framing as that may also make it easier to use metal parts such as post to beam caps. Does that answer the query? If not, have you a photo or a link to a photo?