Just in case anybody finds this in a search sometime, the two are not the same as the Sieg has a larger spindle nose, but I was able to fit a Sieg SC6 backplate to a Chester DB10 Super by making a cast iron sleeve to fit inside the backplate.
Lathe Sieg SC6 Chester DB10 Super (2019)
Spindle nose 52mm 50mm
Plug bolt PCD 75mm 75mm
Plug bolt hole dia. 20mm 20mm
Brian