First of all, welcome to the boards! Glad to have you here.
Definitely an odd duck you have there. Not commonly seen, especially with the second set of numbers so far away from the first.
While not common, these have been seen in the wild before in various formats. In the first format, a large 70 (or 71) followed by the arsenal stamp and then a 5 or 6 digit S/N is often seen on rectangle arsenal guns:
Then every once in a while you will see a carbine without the rectangle stamping, but with very similar stampings, though maybe he 70 isn't as large, but has a clear 70 + arsenal #+ some two digit number (33 is often seen like in yours) + S/N:
In your carbine's case, I would guess this is a 0223 produced carbine (just like the above) and the #'s on the bottom are the S/N and correspond to the 4372th carbine in this particular lot. The DN may have been stamped at production, or most likely were marked there during decommissioning/export/import.