Just bought a DT175MX (2K4 motor)

The reed valve appears to be two stage ie smaller windows with thinner material inside the main reed.

My question is should these smaller inner petals, cover/overlap the opening in the main reed petal ?

as can be seen on the photos, on one side two petals cover and on the other side the two first stage petals leave a gap .

Look like Boyesen Reeds which i've used years ago. They should cover the holes in the main reeds in width & length but they do get weakened over time & can stand up a bit. You'll know if the gap is too much as will be hard to start. But they get blown shut straight away anyway as the piston comes down. Providing they're wide & long enough i'd turn them over [be careful tightening those small screws]. The worst that can happen is they'll brake off but are sort of digestible compared to originals. I turned over those bits on my kids YZ80 [in 1980 lol] as got bent 'way' up on methanol fuel which softened them but they worked ok turned over halfway through that day although i probably ditched them for originals in the end. The theory behind your's was--they were meant to give the advantage of better low end power sucking through the small opening & good top end when both open. [All debatable of course]. There's plenty of other carbon type reeds out there nowdays.
Think Welcome is in order too, so Welcome from NZ. Just going to add, when we used them they said to discard the original stops [bad move i think & possibly half my trouble on our one] & they provided a small narrow flat bar to screw across on original screws. I think original stops as yours is--is best.

Thank you
I thought they should cover the hole to stop blow back but wanted to check