Is it coincidence that the B-2 and YB-49 flying wings have exactly the same wingspan? Development of the Northrop Grumman B-2 Spirit began as far back as 1979; however, this was nearly thirty years after the last flight of Northrop's earlier flying wing the YB-49.

There aren't many apparent similarities: engine position, wing-sweep, shape and control surfaces are all different. Yet they have identical wingspans of 172 feet or 52.4 m.

Is there something special about this particular size? Did Northrop mutate their earlier design (through wind-tunnel testing etc.) from one to the other, or is it purely coincidence?

 B-2 source

 YB-49 source
A random guess without any supporting information. (please edit or delete if this turns out to be inaccurate)

I would guess the logistics of manufacturing. It could the space needed for handling the aircraft in and/or out of manufacturing buildings.
The B-2 program was wildly expensive due to the large number of new technologies involved.

So I guess it was a prudent, maybe even progam-saving decision, to use existing manufacturing facilities are far as possible.