That set was supplied by Emerson Radio & TV Corp. The Allen B. DuMont Labs sold their TV set manufacturing division to Emerson in 1958, along with the rights to use the DuMont name and logo. The DuMont branded sets supplied from that point on were designed and manufactured by Emerson. These were of inferior quality to what DuMont had built.

Emerson had the distinction of having the only TV set rejected for being unsafe to use by Consumer Reports in 1959. This was a B&W table model on legs, and carried the DuMont name. It was a series filament, hot chassis set and the chassis mounting bolts were exposed on the cabinet bottom, and were live with AC. CU rejected the set as unsafe and did not test it further.

The only color sets ever sold by Allen B. DuMont Labs were 21" round tube models using an RCA chassis. See one here:

http://www.earlytelevision.org/21inchcolor.html

Later DuMont branded round color sets supplied by Emerson in 1960 appear to have an RCA chassis. The rectangular model pictured above appears to be mid-sixties vintage.