I can ALMOST sympathize with the guy who did this ... AFAIK, there are no single bussbar panels, and you really don't have this problem considered when they make panels. Rather than double-lug the breaker, the correct method would be to make the splice before the breaker - say, by connecting the supply wire to two pigtails - and then attaching the pigtails to the breaker.

There still remains one BIG concern: I strongly suspect an illegal / non-permitted service change was performed, to replace a fusebox with circuit breakers.

I say that because that house has 120v service .... something that pre-dates WW2. Had a permit been pulled, the PoCo would have almost certainly replaced the service with a modern 240v service.

The house needs a detailed examination by a sparky. When that house was made, it was common to fuse the neutral as well as the hot - something we are not allowed to do these days. Add to that the age of the wiring, other improper 'upgrades' over the years, etc ... and there's a lot of room for error.

Heck, they may have even negated the 'water bond/ground' with a length of plastic pipe.