Answer = #OX2 - #OX4
Using a bit of artistic license for the term 'stamp' (perforated, gummed, and used on mail), I think this is a unique occurrence for a US stampů
On March 16, 1877 the first official seal of the U.S. Post Office Department was delivered to the Dead Letter Office (#OX1). The label features the head of Liberty in its central vignette and can be distinguished by the words "Post Obitum" repeated in the background (literally meaning "after death"). It was printed by the National Bank Note Company and this is incorporated into the stamp design in the bottom frame.
But by 1879 the USPOD needed a less specific design because local postmasters were finding it impractical to forward every piece of problem mail to the Dead Letter Office in Washington. The postmasters and the USPOD realized that much of the problematic mail could be delivered if the official seals were distributed to the post offices themselves. The previous background design was changed away from the Dead Letter reference "Post Obitum" and to a lace pattern.
Also by 1879 Congress had driven the merger of the security printer companies, including National, into a single entity; the American Bank Note Company. But while the National Bank Note Company name remained in the lower border, they added 'American Bank Note Company' to the salvage as shown above.