It's unclear if you're referring to large nozzles with loads or nozzles with large loads. I'll assume you mean the latter.

If you have one expansion joint with stiffness k, and then compare it to two expansion joints with stiffness k installed in series, then the effective resistance is (sum(k^-1))^-1, or k/2.

So, yes, two expansion joints are better than one. But they're also more expensive and themselves add weight.

You mentioned tank settlement and nozzle bulge, but thermal expansion is often a concern, too.

Tank nozzle expansion joints (or ball joints) should themselves be generally installed perpendicular to the nozzle, since that configuration is the only one that addresses displacement from all three sources. But putting all things in perspective, displacement hasn't been defined here.