You don't have any problems.
It seems it's the version Helicobloc from Verney-Carron, manufactured during 1950th, proofed with 1100kg/cm² = 15635psi,
right barrel ***** = cylinder, no choke
left barrel *** = 1/2 choke.
1 1/4 oz lead shot 2,5mm (No.7), 1350fps in a 12 x 70mm cardridge is a normal load to hunt pheasants,I do it every year in autumn.
With steel shot you will have problems with the barrels.
If it's a Helicobloc, it doesn't look like any I've seen previously. And I've certainly never seen one with twin lumps.
I have a V-C catalog from 1999. It looks like the "Rustic" model from V-C's Jet line of sxs, but the photos of the Rustic aren't detailed enough to tell for sure. At that time, V-C was marketing two types of sxs: Jet and Helux. They state that the guns are made for them in the European union. The Helux definitely looks German. Harder to tell with the Jet. My initial thought was Spanish, but in the case of the original poster's gun, that doesn't seem to fit either. I haven't seen anything out of Spain using those twin parallel lumps.
Unless the 1/2 or mod choke is tighter than one would expect, I'd guess that it would be OK with steel as large as US 4's, if you had to use steel in the gun. It does have the double proof, so pressure should not be an issue.