The 13/1 marks indicate the gun is underbored. Standard 12 bore diameter is .729; 13/1 indicates a bore diameter of .719. Good to know that, because measuring the bores allows you to tell how much, if any, the barrels have been honed.
"Choke" on both barrels indicates that the gun came with at least some choke in each, but maybe no more than .008, which would be about improved cylinder as we Americans use the term; about quarter choke in British terminology. Only way to know for sure how much choke is to measure the bores and the choke constriction.
