It's a nice dilemma to have, they both appear to be OK.
My Copy has -1C at the end of the ZTSP # BOTH SIDES
I live in Doncaster & remember going into Angies Records when it was in the Market Place.
Many Okeh DEMO's there in a box however, Photostat Labels
& Vinyl if Memory serves, Counterfeit Copies.
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There are different presses with OKeh & as Dave says Different -A, -B, -C etc depending on Stamper
Here's a couple of odd Stock Copies Different Label Variations & I have seen the White DEMO
-1D
Notice this one has ZSP on the Label but JZTSP in the Deadwax
-1B
Notice this one has JZSP on the Label but ZTSP in the Deadwax