Your first two children only had one middle name. ? If we have a boy we are tempted by an unusual first name. We were planning on having my father's name as one middle name. The thing is it is not the sort of name he would be likely to want to use use if he hates his first name. It's not a horrid name but a bit dated. My husband wonders if we should add a second middle name to give options. Our fist two only have one middle name each.
DD and DS2 both have 2 middle names, the second of each is slightly fanciful. DS1 only has one but as he felt left out has started using my late FIL's (very unusual/actually quite cool) middle name as well.
My brother Has two middle names. Me and my sister each have one. Never been an issue for me, in fact if I ever have a boy he'll also have two middle names (family names) even though dd only has one middle name.
My first three DC have one middle name but this one due in March will have two. This is because I want to give her my late grandma's name as a middle name but the initials would spell out something a bit silly so I'm going to break it up and throw my name in there too
DS1 has two middle names due to something relating to his birth. DS2 has one but refuses to acknowledge it. DH has one middle name I have none and DB has one. FIL has about a million (slight exaggeration)