Argh! How annoying for you. I always had one bigger for about 6-8 months
They would switch every now and then depending on which side DS preferred flow-wise. One has more holes and sprays (which he preferred when I was engorged) and one has two big holes and is like a fire hose (which he preferred when I wasn't as full).
TBH, even my DH couldn't pick which one was bigger (or maybe he was just being nice...) so it wasn't *that* bad but I could tell, mainly because my bra didn't fit right