Concentric Needle Jets - found two different jets - same number ?

Before I go the Premier route due to carb issues on the concentric thought I'd sort out the spare carb jets and see what I have and rebuild some of the carbs.
Started with the needle jets of which I have may have 12 loose ones. I found that I have an assortment of two different jets. All are106 but have two different lengths and different jet bores. All the longer jets have larger openings in the top and smaller openings in the bottom ( the threaded end) ! This cannot be wear. I think that all came from Commandos, either 30, or 32mm carbs.
This makes no sense to me at all, but thinking the collective have a simple answer. Trying to imagine how they would function being so different. Assume they require different needles?
See attached pics.
Currently running two sets of concentric carbs and and I have no idea what is fitted in them in the way of needle jets, I could well have mismatched ones when I cleaned and rebuilt the carbs and fitted jet holders with needle jets already fitted, not something I would think of inspecting if they looked clean.

The small orifice at the top of the needle jet is for a 2 stroke carb. The 2 stroke carb has the jet orifice at the top and the 4 stroke carb has the jet orifice at the bottom of the needle jet. The other difference is that the 2 stroke needle jet does not have the air bleed in the hexagon.
ando

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Needle Jets

In 1969 a new needle jet, needle jet holder and needle , designed specifically for 4 stroke carburetters, was introduced to improve low to mid-range performance. The differences between the parts are;
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New
Needle Jet 13/16" (2.06cm) long cross-drilled"

Old
11/16" (1.74cm) long".

L.A.B. said:

In 1969 a new needle jet, needle jet holder and needle , designed specifically for 4 stroke carburetters, was introduced to improve low to mid-range performance. The differences between the parts are;

Click to expand...

ando said:

The small orifice at the top of the needle jet is for a 2 stroke carb. The 2 stroke carb has the jet orifice at the top and the 4 stroke carb has the jet orifice at the bottom of the needle jet. The other difference is that the 2 stroke needle jet does not have the air bleed in the hexagon.

Click to expand...

That answers that. It shows how long I've been keeping parts, and how observant I am !
Will see what's in the fitted carbs now.
Cheers guys.
Andy