  We discuss how electromagnetically dualizing a 1-form to a 2-form in AdS$_5$
exchanges regular and alternate boundary conditions, and thus gauges the
originally global $U(1)$ symmetry in the dual field theory. The generalized
symmetry current dual to the 2-form in the bulk is identified as the dual field
strength of the gauged $U(1)$, and the associated double-trace operator with a
logarithmically running coupling is just the gauged $U(1)$ Maxwell action.
Applying this dualization to an AdS Maxwell-Chern-Simons theory dual to a
global $U(1) \times U(1)$ model with an 't Hooft anomaly results in a theory
with a modified field strength that holographically realizes a 2-group
symmetry. We explicitly carry out the holographic renormalization to verify
this, and discuss the generalization to other rank fields in other dimensions.
