Fox Collectors

Hey all,
I took my Fox Sterlingworth 12 ga 1920's era to the range with some mild #4 & #00 buck reloads. They guy at the counter told me not to shoot the #00 out of the left barrel because it is "full choke", while the right is "modified. He even put a measuring gauge to it to show me.
Question is: is this common and/or the norm for this shotgun?
Thanks!

I can't think of any reason not to shoot lead #4 buck out of any full choke barrel. Most 28-, 30- and 32-inch Fox-Sterlingworths started life with full choke in the left barrel.

Thanks for the reply. He did say it was ok to shoot #4 out of the left barrel, but advised me not to use #00 in the left. Right side was ok for both. And thanks for clearing up my question about the choke sizes in the barrels. I didn't know they were made that way.