Winchester Model 24 |General Discussions & Questions|Forum|Winchester Collector

Hello,  I have a model 24 that I’m having trouble getting accurate information on. The shotgun in question is a low number(362x), which indicates 1940 manufacture.  However, my consternation comes with this shotgun having one octagon and one round barrel. It’s 12 gauge and all the information I can find indicates that only round barrels were produced.  The gun also has a checkered forearm and grip, which I’m sure are not factory produced. The wood appears to be well fitted and possibly original to the gun. Forearm has #90 stamped into the wood and buttstock has correct Winchester black plastic buttplate.Looking down the sight line, left barrel is octagonal and right is round. Left barrel has all of the standard Winchester markings.  Both barrels have proof stamps. Round barrel has no other markings on top.  Bottom marks indicate octagon as Modified and round as full choke.There is also a second serial number(matching) stamped on the locking lug of the octagon barrel.

Any insight or thoughts would be appreciated.