Teeth on gears confusion

I'm really confused guys I have counted the teeth on my gears and things don't quite add up.

I have a gearbox in bits.
The gears I have are.

1st - 14 & 46
2nd - 20 & 37
3rd - 29 & 35
4th - 41 & 45
5th - 50 & 37

A ra box has.

1st - 14 & 46
2nd - 20 & 37
3rd - 33 & 42
4th - 44 & 42
5th 50 & 37

A rb box has.

1st - 15 & 46
2nd - 17 & 39
3rd - 26 & 43
4th - 33 & 42
5th - 45 & 41

It looks like I have a random 3rd gear.
And a rb 5th in the place of 4th.

But the 4th gear I have looks like a 4th gear. Just has the same amount of teeth as the rb 5th.

Looking at those specs.
My 4th and the rb 5th have the same amount of teeth on each gear. But they are on oposite shafts?